Hmm, you’re right… I think I got excited after seeing it work the first time and failed to try subsequent times 
I do have a new note to add - the logout redirect seems to work directly after receiving an “Authorization timed out, or you have switched browsers. Please try again,” message. It seems to happen when trying to log in very quickly after logging out.
The clip below shows a failed logout redirect at first, then at 13 seconds, it shows the redirect working after the message was displayed.