imap and .newsrc.eld getting out of sync

[Par Kurlberg]

I read mail via nnimap from two computers. Occasionally folders get
out of sync, e.g., from my laptop I can see emails in (say) INBOX,
whereas from my desktop the same email is in the INBOX folder is
"gone".  However, the message is really in the imap folder on the
server (coincidentally I'm running dovecot); I can check this with
other imap mail clients such as thunderbird. I can "recover" the lost
message by deleting the corresponding list entry in .newsrc.eld, and
this makes me believe there is a problem with the local cache getting
out of sync with the imap folder on the server.

Any ideas how to fix this?  (Is there a quick way to resync the local
cache against the server?)

Any ideas how to debug it?

Best,
Par