Update
I’ve narrowed the problem down to the global Inbox. I used to have unified inboxes, but if I uncheck that in DT prefs, then I can get expected behaviour in the dbase specific inboxes, but still have this odd behaviour in the global inbox.
I have tried to rebuild the inbox, but to no avail - I still get the odd behaviour.
I’m now wondering if I should delete that inbox, but I’m open to other suggestions!
Thanks in advance!