Moving data dir - Autoconfig.php getting overwritten? (snap install)

hi all

Trying a snap install for a change (tried & failed with docker, several tutorials and NCPi so far with no luck over the last 2mo - giving snap a go now before I give up entirely!)

I can’t seem to change the data directory to my HDD (which appears to be mounted correctly at ‘/media/nextdata’)

I am using https://github.com/nextcloud/nextcloud-snap/wiki/Change-data-directory-to-use-another-disk-partition

However the changes I make to autoconfig.php are not sticking. I change it as the instructions say - but when I navigate to the web interface (after restarting or dis/enable) it complains I do not have the .ocdata file in the data directory, and I reopen autoconfig.php again at this point to find that it has been reset - the commented out line is reinstated and my new line is nowhere to be seen.

Given that I already moved the data to the new location then the web interface is correct., as it is back to looking in the snap dir for the data, which has gone. The mystery I can’t figure out is why autoconfig.php is getting overwritten. Any ideas or further tests I could try please?

I have also edited the ‘datadirectory’ in config.php to no avail…

Thanks in advance!

Al