NCP nc-encrypt: fuse device not found / fusermount exited with code 256

I’m running nextcloudpi for a year in a docker container (portainer). Now I want to have a second container for nextcloudpi with nc-encrypt enabled.
When I do so, I get the following error with a red dot next to the apply-button:


[ nc-encrypt ] (Wed Mar 9 13:37:34 UTC 2022)
Maintenance mode enabled
/bin/fusermount: fuse device not found, try 'modprobe fuse' first
fuse.NewServer failed: fusermount exited with code 256
{"reqId":"vqqTVbUIVR1QL3dCjfNb","level":2,"time":"2022-03-09T13:37:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Temporary directory /var/www/nextcloud/data/tmp is not present or writable","userAgent":"--","version":"23.0.2.1"}
{"reqId":"vqqTVbUIVR1QL3dCjfNb","level":2,"time":"2022-03-09T13:37:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Temporary directory /var/www/nextcloud/data/tmp is not present or writable","userAgent":"--","version":"23.0.2.1"}
{"reqId":"vqqTVbUIVR1QL3dCjfNb","level":3,"time":"2022-03-09T13:37:36+00:00","remoteAddr":"","user":"--","app":"PHP","method":"","url":"--","message":"fopen(/data/nextcloud/data/data_dir_writability_test_6228ada00b844.tmp): failed to open stream: Permission denied at /data/nextcloud/lib/private/legacy/OC_Util.php#792","userAgent":"--","version":"23.0.2.1","exception":{"Exception":"Error","Message":"fopen(/data/nextcloud/data/data_dir_writability_test_6228ada00b844.tmp): failed to open stream: Permission denied at /data/nextcloud/lib/private/legacy/OC_Util.php#792","Code":0,"Trace":[{"function":"onError","class":"OC\\Log\\ErrorHandler","type":"::"},{"file":"/data/nextcloud/lib/private/legacy/OC_Util.php","line":792,"function":"fopen"},{"file":"/data/nextcloud/lib/private/Console/Application.php","line":157,"function":"checkServer","class":"OC_Util","type":"::"},{"file":"/data/nextcloud/console.php","line":98,"function":"loadCommands","class":"OC\\Console\\Application","type":"->"},{"file":"/data/nextcloud/occ","line":11,"args":["/data/nextcloud/console.php"],"function":"require_once"}],"File":"/data/nextcloud/lib/private/Log/ErrorHandler.php","Line":92,"CustomMessage":"--"}}
Your data directory is invalid
Ensure there is a file called ".ocdata" in the root of the data directory.

Your data directory is not writable
Permissions can usually be fixed by giving the webserver write access to the root directory. See https://docs.nextcloud.com/server/23/go.php?to=admin-dir_permissions.

An unhandled exception has been thrown:
Exception: Environment not properly prepared. in /data/nextcloud/lib/private/Console/Application.php:164
Stack trace:
#0 /data/nextcloud/console.php(98): OC\Console\Application->loadCommands()
#1 /data/nextcloud/occ(11): require_once('/data/nextcloud...')
#2 {main}{"reqId":"vqqTVbUIVR1QL3dCjfNb","level":3,"time":"2022-03-09T13:37:36+00:00","remoteAddr":"","user":"--","app":"PHP","method":"","url":"--","message":"fopen(/data/nextcloud/data/nextcloud.log): failed to open stream: Permission denied at /data/nextcloud/lib/private/Log/File.php#84","userAgent":"--","version":"23.0.2.1"}

Not quite sure what causes the issue.
When I access ncp web interface (:4443), it redirects to :4443/decrypt with a blank page.
When I access nc, it says that the data directory is invalid and not writable.
When I reboot the container and then access nc, it asks for the password to decrypt but it says it’s wrong.

Any help appreciated.

The 2 NextCloudPi Containers are managed by Portainer. Portainer is installed on Proxmox.
ncp version: 1.46.9
nc version: 23.0.2.1