I sent some messages in Russian... and then I tried to search for them with "search in history" but without success. No messages were found. English search is working ok.
Which version of Mattermost or GitLab are you using? - Mattermost Team EditionVersion:2.0.0 Build Number:5950
Are you on a new install or an upgrade? - New install
A link to documentation you’re using to install and the specific step at which you’re failing - http://docs.mattermost.com/install/prod-rhel-7.html
Relevant output of error logs in mattermost.log - no errors in log.