Music stored on Internal memory does not appear in any player

Have strange problem. On OnePlus 3T (without storage card) uploaded music to Music folder (tried different names, no use). All the players that I've tried does not see and can't play music. Files are visible in file browser, they can be played inside browser but is impossible to use any of media players. In some players tried "rescan device" function, also no use.

Even on browser based Airdroid Music folder is empty while files are visible in file browser.

Any ideas, tips?