I’m encountering the same issue. Did you find a workaround for this to add rows or columns to tables without the use of the pop-up menu. Keyboard shortcuts don’t seem to work either.
Thanks for reporting, I’m still investigating, but it seems that’s due do a change in how menu works in macOS 15.0+. The menus are now stealing the focus from the table cell, so we don’t know which cell was selected and the actions are not enabled.