Can also confirm this issue with blue circle not showing number of unread messages and new messages not showing up in latest messages preview.
It seems only IMAP is affected.
Google-MfE account still works fine.
Deleting and recreating IMAP account didn`t help, but if I use POP instead of IMAP it works...
(However when using POP, messages are not marked read when downloaded with PC mail client - annoying!)