Url pencil icon does not toggle editing modal

[tinykite]

While using the dev-preview I noticed there is a pre-written "URL" mark annotation available in the block content editor of Sanity that does not seem to behave predictably.

The parent button in the main toolbar:

In the rendered block content preview itself:

The selected text is rendered as a link, and there's a toolbar that pops up after clicking on it, but after at least two dozen attempts, the pencil icon has opened the URL modal only twice. I found this confusing, so I tried it in Chrome and Firefox and had similar difficulty in both browsers (any with any browser plugins that might interfere with page rendering disabled).

I have also noticed that frequently the toolbar will momentarily appear and then disappear as soon as a link is clicked (with no discernible changes to pointer events)

The issue seems to be specific to this toolbar, not all modals or all types of overlays (I've had no issues creating a custom image gallery type that pops up a modal for uploading multiple images, which seems to also rely on a toolbar of buttons)