Audio files not found (of a lot of files)

I’ve this problem with a large number of files and folders (about 60GB of mp3).
I’ve tried to change folders for start the search of mp3 ar different point (subfolders), the results are always partial and different, but seems that when a file or subfolder is find, it will be added also the next time when i try to search starting on a upper level.
Maybe there’s a limit on node/folder search and/or a problem to “touch” the file for the first time.
Tried also with console/occ, same results.
The files are on a external SD card and are copied there with a copy command on server and not by nexcloud web browser, but there all all reachable (and playable) on brower trought nextcloud


Executed (again) on terminal:
sudo chown -R www-data:www-data /mnt/sdcard…(path to audio files)

Hope that this can help someone in the future and thanks to me :wink: