Teachers cannot access reports and settings
By default, Level up! gives access to restricted pages (settings, reports, logs, ...) to teachers, however when the plugin is used for the whole site this permission is only granted to managers.
To remedy this, a role allowing the permission (see which permission in section below) must be given to the relevant users are the site level.
If Level up! is used per course, you should double check that your typical teacher roles have been granted the permission.
Which permission to give?
Prior to Level up! v3.6.1, teachers had to be given the permission block/xp:addinstance to access the restricted pages. This permission also allowed them to add the block to pages.
Since Level up! v3.6.1, the permission block/xp:manage was added to separate the permission to access restricted pages from the one to add the block to pages. The latter permission has to be given to teachers.