Permissions for Classes missing

As stated here with every call of python migrate the default permissions are created for new models.

What could be the reason that permissions are not created for classes from a certain
These are classes that were created normally (with models.Model). If you want to assign permissions to individual users for these models in django-admin, exactly these models do not show up.
In an associated the models were registered with @admin.register() for the admin-backend.

The real problem is that administrators see these classes/models in their backend and are able to edit them. A part of the users (which belongs to the group staff) should also see these models, but not be able to edit them. However, since permissions cannot be assigned to users or user groups in Django admin (and they don’t show up when getting all permissions via Permission.objects.all()), this fails.

Also adding default permissions to the classes Meta and running migrate does not change a thing.

Does anyone have any ideas?

There are a number of different possible reasons why this could occur.

However, rather than chasing down some number of theoretical possibilities, it might be easiest to just try rebuilding your database from scratch to see what’s happening. Change your DATABASES default to point to a new database and run migrate. See if the permissions are being created in that new database.
This will help determine whether the problem is in the original database or in your code.