Logfile stays empty

I have issues syncing or uploading some files, both with the client and using the webinterface.

Using the webinterface it get a message popup at the top saying ‘An unknown error has occurred’.

When i look at admin/logging i see no entries. Also on the server nextcloud.log is empty (i tried removing it, it gets recreated but empty - so no permission issue)

I tried turning on the debug logs by adding

"log_type" => "file",
"logfile" => "nextcloud.log",
"loglevel" => "1",

to the config/config.php file and restarting the service but no change.

I am using the docker nextcloud:fpm image which atm is version 16.0.1

How can i get to see more verbose output than ‘unknown error’ ?

Same issue still in 16.0.3