Hi all, got the same problem and found the solution on GIT nextcloud
(filescan retrun "entry will not be accessible due to incompatible encoding" · Issue #3136 · nextcloud/server · GitHub)
Just installed convmv and run:
convmv -f utf-8 -t utf-8 -r --notest --nfc <nextcloud-data-folder>
After this a simple reindex helped me to see my data in Nextcloud:
php occ files:scan --all