session.query(pycram.orm.base.ProcessMetaData).all() returns only one object

[Leusmann]

Summery

I am trying to query all ProcessMetaData from my local postgres database, using the ORM.
But using the following command response = session.query(pycram.orm.base.ProcessMetaData).all() returns only a list containing one object instead of all objects as expected.

Detailed

I am using the following postgres version:
PostgreSQL 14.10 (Ubuntu 14.10-1.pgdg20.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0, 64-bit

My ProcessMetaData has the following definition:

pycram=# \d "ProcessMetaData" 
                                           Table "public.ProcessMetaData"
     Column     |            Type             | Collation | Nullable |                    Default                    
----------------+-----------------------------+-----------+----------+-----------------------------------------------
 created_at     | timestamp without time zone |           | not null | CURRENT_TIMESTAMP
 created_by     | character varying(255)      |           | not null | 
 description    | character varying(255)      |           | not null | 
 pycram_version | character varying(255)      |           |          | 
 id             | integer                     |           | not null | nextval('"ProcessMetaData_id_seq"'::regclass)
Indexes:
    "ProcessMetaData_pkey" PRIMARY KEY, btree (id)
Referenced by:
    TABLE ""Code"" CONSTRAINT "code_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Color"" CONSTRAINT "color_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Designator"" CONSTRAINT "designator_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Object"" CONSTRAINT "object_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Pose"" CONSTRAINT "pose_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Position"" CONSTRAINT "position_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""Quaternion"" CONSTRAINT "quaternion_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""RobotState"" CONSTRAINT "robotstate_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE
    TABLE ""TaskTreeNode"" CONSTRAINT "tasktreenode_process_metadata_id_fkey" FOREIGN KEY (process_metadata_id) REFERENCES "ProcessMetaData"(id) ON UPDATE CASCADE

It contains the following data:

pycram=# select * from "ProcessMetaData";
         created_at         | created_by |                     description                     |              pycram_version              | id 
----------------------------+------------+-----------------------------------------------------+------------------------------------------+----
 2023-12-22 14:16:49.281148 | nleusmann  | Unittest: All that is gold does not glitter, 0      | af343656dd2d615259c5df4543b56260cf8d358e |  7
 2023-12-22 14:17:01.399586 | nleusmann  | Unittest: Not all those who wander are lost; 1      | af343656dd2d615259c5df4543b56260cf8d358e |  8
 2023-12-22 14:17:13.865826 | nleusmann  | Unittest: The old that is strong does not wither, 2 | af343656dd2d615259c5df4543b56260cf8d358e |  9
 2023-12-22 13:22:11        | nleusmann  | Database merger Unittest: Example pick and place 0  | af343656dd2d615259c5df4543b56260cf8d358e | 10
 2023-12-22 13:22:24        | nleusmann  | Database merger Unittest: Example pick and place 1  | af343656dd2d615259c5df4543b56260cf8d358e | 11
 2023-12-22 13:22:36        | nleusmann  | Database merger Unittest: Example pick and place 2  | af343656dd2d615259c5df4543b56260cf8d358e | 12
 2023-12-22 13:22:11        | nleusmann  | Database merger Unittest: Example pick and place 0  | af343656dd2d615259c5df4543b56260cf8d358e |  1
 2023-12-22 13:22:24        | nleusmann  | Database merger Unittest: Example pick and place 1  | af343656dd2d615259c5df4543b56260cf8d358e |  2
 2023-12-22 13:22:36        | nleusmann  | Database merger Unittest: Example pick and place 2  | af343656dd2d615259c5df4543b56260cf8d358e |  3
 2023-12-22 13:22:50        | nleusmann  | Database merger Unittest: Example pick and place 0  | af343656dd2d615259c5df4543b56260cf8d358e |  4
 2023-12-22 13:23:03        | nleusmann  | Database merger Unittest: Example pick and place 1  | af343656dd2d615259c5df4543b56260cf8d358e |  5
 2023-12-22 13:23:15        | nleusmann  | Database merger Unittest: Example pick and place 2  | af343656dd2d615259c5df4543b56260cf8d358e |  6

When using the response = session.query(pycram.orm.base.ProcessMetaData).all() command, the only value that gets returned is the following:

[ProcessMetaData(id=6, created_at=datetime.datetime(2023, 12, 22, 13, 23, 15), created_by='nleusmann', description='Database merger Unittest: Example pick and place 2', pycram_version='af343656dd2d615259c5df4543b56260cf8d358e')]

Which is the most recently added object.
Curiously the count = session.query(pycram.orm.base.ProcessMetaData).count() returns the correct amount of 12.

Utilizing the select statement.

select_statement = sqlalchemy.select('*').select_from(pycram.orm.base.ProcessMetaData)
select_result = session.execute(select_statement).all()

I receive the expected return value:

[(datetime.datetime(2023, 12, 22, 14, 16, 49, 281148), 'nleusmann', 'Unittest: All that is gold does not glitter, 0', 'af343656dd2d615259c5df4543b56260cf8d358e', 7), (datetime.datetime(2023, 12, 22, 14, 17, 1, 399586), 'nleusmann', 'Unittest: Not all those who wander are lost; 1', 'af343656dd2d615259c5df4543b56260cf8d358e', 8), (datetime.datetime(2023, 12, 22, 14, 17, 13, 865826), 'nleusmann', 'Unittest: The old that is strong does not wither, 2', 'af343656dd2d615259c5df4543b56260cf8d358e', 9), (datetime.datetime(2023, 12, 22, 13, 22, 11), 'nleusmann', 'Database merger Unittest: Example pick and place 0', 'af343656dd2d615259c5df4543b56260cf8d358e', 10), (datetime.datetime(2023, 12, 22, 13, 22, 24), 'nleusmann', 'Database merger Unittest: Example pick and place 1', 'af343656dd2d615259c5df4543b56260cf8d358e', 11), (datetime.datetime(2023, 12, 22, 13, 22, 36), 'nleusmann', 'Database merger Unittest: Example pick and place 2', 'af343656dd2d615259c5df4543b56260cf8d358e', 12), (datetime.datetime(2023, 12, 22, 13, 22, 11), 'nleusmann', 'Database merger Unittest: Example pick and place 0', 'af343656dd2d615259c5df4543b56260cf8d358e', 1), (datetime.datetime(2023, 12, 22, 13, 22, 24), 'nleusmann', 'Database merger Unittest: Example pick and place 1', 'af343656dd2d615259c5df4543b56260cf8d358e', 2), (datetime.datetime(2023, 12, 22, 13, 22, 36), 'nleusmann', 'Database merger Unittest: Example pick and place 2', 'af343656dd2d615259c5df4543b56260cf8d358e', 3), (datetime.datetime(2023, 12, 22, 13, 22, 50), 'nleusmann', 'Database merger Unittest: Example pick and place 0', 'af343656dd2d615259c5df4543b56260cf8d358e', 4), (datetime.datetime(2023, 12, 22, 13, 23, 3), 'nleusmann', 'Database merger Unittest: Example pick and place 1', 'af343656dd2d615259c5df4543b56260cf8d358e', 5), (datetime.datetime(2023, 12, 22, 13, 23, 15), 'nleusmann', 'Database merger Unittest: Example pick and place 2', 'af343656dd2d615259c5df4543b56260cf8d358e', 6)]

But instead of an list of all the different ProcessMetaData stored within my database I only receive an single object.
What is even more surprising is the fact that the counting command returns the :

count = session.query(pycram.orm.base.ProcessMetaData).count()

returns the correct amount of possible objects.

If needed I can provide additional information, please just ask.