Missing .ocdata file / Permissions problems

Hi there,

I’m having issues installing Owncloud 10.8 on my Ubuntu Server. I’m currently trying to move the data folder to a RAID 1 Array mounted at /mnt/raid/. If I leave the Owncloud data folder in the standard installation folder it works fine. If I copy the data folder to the Raid Array and also follow the instructions for changing the data folders I always get the error message that .ocdata is missing.

I have tried giving permissions to www-data via chmod and chown but it seems that it doesn’t make any difference. I have tested if www-data has access to the data folder:

root@schlund:/mnt/raid/Public# sudo -u www-data ls -la /mnt/raid/Public/owncloud/data/
ls: cannot access ‘/mnt/raid/Public/owncloud/data/’: Permission denied

I know this seems more like a linux permission problem, but I don’t really know where to ask.

Owncloud 10.8, downloaded as TAR Ball
Ubuntu 20.04.3
PHP 7.4.3

Thanks in Advance