Dani,
New information: I discovered, looking at some other issues about the new caption keyboard shortcuts, that some of the Beta commands are already in PR 23.3 Release version. Ordinarily, this wouldn't matter if you didn't try to use something that is not supported. I now suspect you were using the shortcut, appropriately, to enter edit mode in the Text Panel.
The command "Edit selected caption text" was an Application level command and a shortcut assigned to it would work in the Timeline (to put the text into edit mode in the Program Monitor) and in the Text Panel (to put the text in the caption tab into edit mode). In 23.3 (and the public Beta version), that shortcut is unchanged, but the edit command in the Text Panel is now "Edit Segment." So your old shortcut doesn't work there.
Workaround: You can assign the same shortcut to the Edit Segment command, and it will work in both places.
In the Beta version, the default assignment for the Edit Segment is the Enter key. So there will be a quick way to enter edit mode via keyboard in the Caption (and Transcript) panel. Major enhancements are coming that use transcripts based on source media as well as sequences for captions.
Stan