XenForo stores secondary user groups in a varbinary list. You might not see this list in human-readable form depending on your version of phpMyAdmin or otherwise in the browse so it might look confusing.
If you need to grab all users that are in a secondary usergroup, here is the query to enter...
Resource Manager 1.1 - Permissions
I've just picked a fight with the new RM permissions, so this guide might be useful for some of you. If you're an expert with XenForo permissions you certainly won't need it, so don't need to waste your time with it.
Case:
You've got two kind of usergroups...