Separate Groups mode restrictions were not honored in the H5P attempts report, which would display users from other groups. By default this only provided additional access to non-editing teachers.
https://moodle.org/mod/forum/discuss.php?d=455636
https://bugzilla.redhat.com/show_bug.cgi?id=2264096
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-80501