Sidebar mailboxs not showing new mail

[wagafo]

I have these in my .muttrc

set check_new=yes
set mail_check=10
set timeout=30
set sidebar_visible=yes
color sidebar_new green default
set sidebar_new_mail_only = no

But in the sidebar mailboxes don't change its color when new mail arrives, and I can't tell if I have new mail unless I open all the folders. It used to work with the same .muttrc when using mutt-patched.
mutt 1-6-2-neo
in Ubuntu 16.10.

[flatcap]

Around the time of this release, upstream Mutt adopted the sidebar, but decided that some of the mailbox checks were too resource intensive (for the default settings).

Try these options:

set mail_check_stats = yes
set mail_check_stats_interval = 30

[wagafo]

Perfect, thank you very much, with those options the mailboxes with new messages are highlighted again.