actually using another browser cured this problem. I assume clearing the cache would have achieved the same.
Now I’n facing an access problem. Can’t create a new file in the web interface when I am using the alternative data location. I assumed cp -a -r /var/nextcloud/common/nextcloud/data/ /path/to/new-location/ (the -a option mainly) should make sure the access rights are kept intact. And if I compare the rights between the original & the new data folder in the command line they are identical.