diff --git a/library/Icingadb/Model/CustomvarFlat.php b/library/Icingadb/Model/CustomvarFlat.php
index c9d0afe67..97b0254fd 100644
--- a/library/Icingadb/Model/CustomvarFlat.php
+++ b/library/Icingadb/Model/CustomvarFlat.php
@@ -101,9 +101,19 @@ public function unFlattenVars(Traversable $flattenedVars): array
                 $step = $m[1];
             }
 
-            while ($source !== null && ! empty($path) && (! is_array($source) || ! isset($source[$step]))) {
-                $step = sprintf($isIndex ? '[%d].%s' : '%s.%s', $step, array_shift($path));
-                $isIndex = false;
+            if ($source !== null) {
+                while (! isset($source[$step])) {
+                    if ($isIndex) {
+                        $step = sprintf('[%d]', $step);
+                        $isIndex = false;
+                    } else {
+                        if (empty($path)) {
+                            break;
+                        }
+
+                        $step = implode('.', [$step, array_shift($path)]);
+                    }
+                }
             }
 
             if (! empty($path)) {
@@ -113,7 +123,10 @@ public function unFlattenVars(Traversable $flattenedVars): array
 
                 $registerValue($data[$step], $source[$step] ?? null, $path, $value);
             } else {
-                $data[$step] = $value;
+                // Since empty custom vars of type dictionaries and arrays have null values in customvar_flat table,
+                // we won't be able to render them as such. Therefore, we have to use the value of the `customvar`
+                // table if it's not null, otherwise the current value, which is a "null" string.
+                $data[$step] = $source[$step] ?? $value;
             }
         };
 
@@ -130,7 +143,12 @@ public function unFlattenVars(Traversable $flattenedVars): array
                 $source = [$realName => $var->customvar->value];
 
                 $sourcePath = ltrim(substr($var->flatname, strlen($realName)), '.');
-                $path = array_merge([$realName], $sourcePath ? explode('.', $sourcePath) : []);
+                $path = array_merge(
+                    [$realName],
+                    $sourcePath
+                        ? preg_split('/(?<=\w|])\.|(?<!^|\.)(?=\[)/', $sourcePath)
+                        : []
+                );
             } else {
                 $path = explode('.', $var->flatname);
                 $source = null;
diff --git a/library/Icingadb/Web/Control/SearchBar/ObjectSuggestions.php b/library/Icingadb/Web/Control/SearchBar/ObjectSuggestions.php
index ae050f130..ad35c7456 100644
--- a/library/Icingadb/Web/Control/SearchBar/ObjectSuggestions.php
+++ b/library/Icingadb/Web/Control/SearchBar/ObjectSuggestions.php
@@ -148,7 +148,7 @@ protected function fetchValueSuggestions($column, $searchTerm, Filter\Chain $sea
         }
 
         $columnPath = $query->getResolver()->qualifyPath($column, $model->getTableName());
-        list($targetPath, $columnName) = preg_split('/(?<=vars)\.|\.(?=[^.]+$)/', $columnPath);
+        list($targetPath, $columnName) = preg_split('/(?<=vars)\.|\.(?=[^.]+$)/', $columnPath, 2);
 
         $isCustomVar = false;
         if (substr($targetPath, -5) === '.vars') {
@@ -212,15 +212,16 @@ protected function fetchColumnSuggestions($searchTerm)
 
         // Custom variables only after the columns are exhausted and there's actually a chance the user sees them
         $titleAdded = false;
+        $parsedArrayVars = [];
         foreach ($this->getDb()->select($this->queryCustomvarConfig($searchTerm)) as $customVar) {
             $search = $name = $customVar->flatname;
-            if (preg_match('/\w+\[(\d+)]$/', $search, $matches)) {
-                // array vars need to be specifically handled
-                if ($matches[1] !== '0') {
+            if (preg_match('/\w+(?:\[(\d*)])+$/', $search, $matches)) {
+                $name = substr($search, 0, -(strlen($matches[1]) + 2));
+                if (isset($parsedArrayVars[$name])) {
                     continue;
                 }
 
-                $name = substr($search, 0, -3);
+                $parsedArrayVars[$name] = true;
                 $search = $name . '[*]';
             }
 
diff --git a/test/php/library/Icingadb/Model/CustomvarFlatTest.php b/test/php/library/Icingadb/Model/CustomvarFlatTest.php
new file mode 100644
index 000000000..b75733c18
--- /dev/null
+++ b/test/php/library/Icingadb/Model/CustomvarFlatTest.php
@@ -0,0 +1,121 @@
+<?php
+
+/* Icinga DB Web | (c) 2023 Icinga GmbH | GPLv2 */
+
+namespace Tests\Icinga\Modules\Icingadb\Model;
+
+use Icinga\Module\Icingadb\Model\CustomvarFlat;
+use PHPUnit\Framework\TestCase;
+
+class CustomvarFlatTest extends TestCase
+{
+    const EMPTY_TEST_SOURCE = [
+        ["dict.not_empty.foo","bar","dict","{\"empty\":{},\"not_empty\":{\"foo\":\"bar\"}}"],
+        ["dict.empty",null,"dict","{\"empty\":{},\"not_empty\":{\"foo\":\"bar\"}}"],
+        ["list[1]",null,"list","[[\"foo\",\"bar\"],[]]"],
+        ["list[0][0]","foo","list","[[\"foo\",\"bar\"],[]]"],
+        ["list[0][1]","bar","list","[[\"foo\",\"bar\"],[]]"],
+        ["empty_list",null,"empty_list","[]"],
+        ["empty_dict",null,"empty_dict","{}"],
+        ["null","null","null","null"]
+    ];
+
+    const EMPTY_TEST_RESULT = [
+        "dict" => [
+            "not_empty" => [
+                "foo" => "bar"
+            ],
+            "empty" => []
+        ],
+        "list" => [
+            ["foo", "bar"],
+            []
+        ],
+        "empty_list" => [],
+        "empty_dict" => [],
+        "null" => "null"
+    ];
+
+    const SPECIAL_CHAR_TEST_SOURCE = [
+        [
+            "vhosts.xxxxxxxxxxxxx.mgmt.xxxxxx.com.http_port",
+            "443",
+            "vhosts",
+            "{\"xxxxxxxxxxxxx.mgmt.xxxxxx.com\":{\"http_port\":\"443\"}}"
+        ],
+        ["ex.ample.com.bla","blub","ex","{\"ample.com\":{\"bla\":\"blub\"}}"],
+        ["example[1]","zyx","example[1]","\"zyx\""],
+        ["example.0.org","xyz","example.0.org","\"xyz\""],
+        ["ob.je.ct","***","ob","{\"je\":{\"ct\":\"tcejbo\"}}"],
+        ["real_list[2]","three","real_list","[\"one\",\"two\",\"three\"]"],
+        ["real_list[1]","two","real_list","[\"one\",\"two\",\"three\"]"],
+        ["real_list[0]","one","real_list","[\"one\",\"two\",\"three\"]"],
+        ["[1].2.[3].4.[5].6","123456","[1].2","{\"[3].4\":{\"[5].6\":123456}}"],
+        ["ex.ample.com","cba","ex.ample.com","\"cba\""],
+        ["[4]","four","[4]","\"four\""]
+    ];
+
+    const SPECIAL_CHAR_TEST_RESULT = [
+        "vhosts" => [
+            "xxxxxxxxxxxxx.mgmt.xxxxxx.com" => [
+                "http_port" => 443
+            ]
+        ],
+        "ex" => [
+            "ample.com" => [
+                "bla" => "blub"
+            ]
+        ],
+        "example[1]" => "zyx",
+        "example.0.org" => "xyz",
+        "ob" => [
+            "je" => [
+                "ct" => "tcejbo"
+            ]
+        ],
+        "real_list" => [
+            "one",
+            "two",
+            "three"
+        ],
+        "[1].2" => [
+            "[3].4" => [
+                "[5].6" => "123456"
+            ]
+        ],
+        "ex.ample.com" => "cba",
+        "[4]" => "four"
+    ];
+
+    public function testUnflatteningOfEmptyCustomVariables()
+    {
+        $this->assertEquals(
+            self::EMPTY_TEST_RESULT,
+            (new CustomvarFlat())->unFlattenVars($this->transformSource(self::EMPTY_TEST_SOURCE)),
+            "Empty custom variables are not correctly unflattened"
+        );
+    }
+
+    public function testUnflatteningOfCustomVariablesWithSpecialCharacters()
+    {
+        $this->assertEquals(
+            self::SPECIAL_CHAR_TEST_RESULT,
+            (new CustomvarFlat())->unFlattenVars($this->transformSource(self::SPECIAL_CHAR_TEST_SOURCE)),
+            "Custom variables with special characters are not correctly unflattened"
+        );
+    }
+
+    protected function transformSource(array $source): \Generator
+    {
+        foreach ($source as $data) {
+            yield (object) [
+                'flatname' => $data[0],
+                'flatvalue' => $data[1],
+                'customvar' => (object) [
+                    'name' => $data[2],
+                    'value' => $data[3]
+                ]
+            ];
+        }
+    }
+}