Admin Manual Removal of Users From Group Fails

[shanebee]

I have just encountered this issue a couple of days ago and am still going through the config to see if I messed something up but here is the error I am seeing:

Notice: Trying to get property of non-object in OgBehaviorHandler->groupAudiencegetDiff() (line 171 of /sites/all/modules/og/plugins/entityreference/behavior/OgBehaviorHandler.class.php).

The configuration isn't terribly fancy. I have installed OG and added the selection of groups to the user registration page. They are allowed to select a group but it is not mandatory.

However, when I attempt to remove a user from a group (specifically a user being removed from a group by an admin user) this error is produced. The user is not removed from the group. Their membership remains intact.

Still digging but any thoughts would be awesome.