Can't recover mail from trash on imap server

vsn 6.602. Both Inbox and Trash are 1st Class (all options.) If I delete mail from inbox, it appears in trash. If I go to trash and move back to inbox, it disappears from trash. However, if I go back to inbox it doesn’t appear.

Yet, if I look in Thunderbird (on Win11), I see the message in the inbox but even with a refresh, K9mail doesn’t show it.