Hey there!
I guess I've noticed some kind of problem. Whenever I grant the "mountlogger.scrapheli.log" and all the others to a user group - after a server reatart those get resetted.

I have three groups: default, vip and admin. And I noticed that only the admin mounts are logged but not the other groups. I granted them once all logs - and it seemed to work - but today, after my server restarted once, only the admins are logged again.

Did I do something wrong or is it something else?

Make sure your server is actually saving before shutdown or restart; this is performed automatically if doing a graceful, non-forceful shutdown.

It does so, so I don't think that could be the case

That is generally why permissions wouldn't save, as they are only saved on server save.

But why do all other permissions from other plugins save - but this one doesn't?

Snugglebit

But why do all other permissions from other plugins save - but this one doesn't?

There isn't anything specific about the plugin you mentioned or any different handling of permissions.

Then I don't understand why the permissions of this plugin don't save or what I'm doing wrong.

As far as I understand this plugin, I just need to grant every of the ".log" permissions to every group I want to see the logs of. So "o.grant group default mountlogger.scrapheli.log" for example. The "mountlogger.use" is only for admins - or am I wrong here?

The mountlogger.use permission is needed for all. From the plugin docs:

• mountlogger.use - Required to use the plugin

Alright it's working now, thanks.
I interpreted "Required to use the plugin" as something only admins should be able to do.