Moving messages (from showing a thread as a list) on different accounts to the same folder.

Following use case: I have my INBOX on IMAP, and my Sent folder locally. Sometimes I show a thread as a list (opened in a separate tab).

Then I mark all messages of the thread, press M, and select a folder where that thread should go.

Expected result: All messages are moved.
Actual result: Only the messages from INBOX are moved.

Moving the remaining messages from Sent "again" then works just fine.

It seems there is something going internally that prevents moving messages from multiple accounts being moved together.

No file, test, or entry point is named. Reproduce the case with an IMAP INBOX and a local Sent folder, display a thread as a list, select all messages, and move them to another folder; done means messages from both accounts move together, while moving the remaining Sent messages again continues to work.

Written by the indexing model from the issue text.