Hello,
Thank you all for your help, just in case someone has the same issue, the following solution solved mine:
ssh to the server and clear cache.
rm /var/lib/check_mk_agent/cache/chrony.cache
And generate cache again by run check_mk_agent
check_mk_agent
Update: Clear cache only fix it temporarily. Need start check_mk-async.service to fix it permanently.
systemctl enable check_mk-async.service
systemctl start check_mk-async.service
systemctl status check_mk-async.service