Can't find nnimap groups by command completion

[jang@pobox.se (Jan Garefelt)]

Finding INBOX by jumping to it using gnus-group-jump-to-group works
like a charm.

Trying to command-complete to find INBOX.foo does not seem to work.

Any suggestions as to what might be causing the problem?

I use xemacs 20.4 and nnimap 0.89. I'm not sure what kind of server I
connect to, but I have a faint recollection that it is a Cyrus server.

Please excuse a newbie if the question already has been answered...

/Jan Garefelt