By a coincidence I hadn't installed private message plugin on my test site. I noticed SQL error
<span>Table 'e10720180621.e107_private_msg' doesn't exist</span>
I checked menu, pm section, admin... there is set class nobody if this this plugin is not installed.
And if you have no permission, this section is not displayed.
Everything looked correct...
and there I saw it, stupid mistypo in original plugin, not installed plugins had wrong numbering