OK, thanks for clearing up the requested partition directory message herring.
Adding destination partitions/doing xfer over telnet doesn't make a difference.
I've had issues over the years w/xferring users. Also in 3.0, I believe, where I wrote:
I've found https://github.com/cyrusimap/cyrus-imapd/issues/2383 (Xfer for a single mailbox doesn't work) which seems to describe the issue. The page contains a patch that was merged in cyrus v3.0. May be that patch was what saved me earlier -- I can't remember exactly.
Was the patch included in later versions? The corresponding line in version 3.4.1 seems to be line 12029 in "imap/imapd.c":
mboxlist_findall(NULL, mbname_intname(mbname), 1, NULL, NULL, xfer_addmbox, &list);
I don't know if I run a toxic combo of virtdomains, altnamespace, and unixhierarchysep. I suppose that other admins are able to xfer users?