Plex Media Server version? Available via Authorized Devices.
Reset permissions for your media folders. See first post linked below for instructions. Please follow the steps in the post even though you have previously checked permissions. It ensures the user PlexMediaServer has access to your media.
If you are still having issues, check the log files for database corruption. Database corruption is easy to spot in the logs. See the second post linked below. You can check yourself or post your log files to the thread (attach the entire ZIP file).
If permissions reset does not help and there are no signs of database corruption in the logs, then do post the log files to the thread. There may be something else going on
https://forums.plex.tv/t/dsm-7-files-not-available/735455/17?u=fordguy61
