If the permission are ok, check to see if the folder has files other than multimedia ones. You might get an error that won't show up in logs. To check switch to emby user and run find command:

su -s /bin/bash emby
emby@raspberrypi:~ $ find /media/touro -ls > /dev/null
find: ‘/media/touro/antisa-desktop/duplicity-full.20190920T085932Z.vol1847.difftar.gpg’: Input/output     error
find: ‘/media/touro/antisa-desktop/duplicity-full.20190920T085932Z.vol1848.difftar.gpg’: Input/output error

Errors above caused the issue with scanning the folder on external ntfs formatted usb disk. Remove the files or move the multimedia files to another folder.

• rasbperry pi 3B+
• emby 4.6.7.0

• https://emby.media/community/index.php?/topic/98114-scan-library-files-results-in-0-items-found/