Can't create or rename Inbox subfolders in Thunderbird

Environment: * Thunderbird 153.0.2 (aarch64) * MacBook Air, M4, Tahoe 26.5.1 When I try to create or rename an Inbox subfolder in Thunderbird it all ''seems’’ to work (no error message), but after pressing “Rename” or Create” nothing happens. Thought I found a workaround: Created a “Temporary” subfolder in “Local Folders” and “moved it" to the Inbox. And it showed up there. (But it was still in the “Local Folders”!). Tried moving a (Spam) email into the Temporary folder under the Local Folders, that worked. Tried moving a (Spam) email into the Temporary folder under the Inbox—it just disappeared! It was no longer in the Spam folder, but did not end up in (either) Temporary folder.