New messages detection does not work in the current version of mutt on openSUSE
Tumbleweed. As a long time mutt user I'm used to shuffle through the list of
folders containing new/unread messages using the 'c' followed by 'space' key
sequence. I narrowed it down to the configure option "--enable-sidebar", which
enables some pseudo graphical functionality for - I guess - mutt newbies.
Rebuilding the otherwise unchanged package with "--disable-sidebar" produces a
normally working mutt again.

I strongly recommend to disable this code until it gets fixed. Thx.