Symptoms

When the user was building out their workflow on the primary site collection the were only able to access groups from the site collection that was onboarded and nowhere else. This was only the case for Appit as SharePoint designer did not have this problem. No error message was thrown, the groups just didn't exist as far as Appit was concerned.
 

Diagnoses

For reasons unknown, when the site collection was made it was somehow made without a Title. Appit uses that property to Name the groupprovider in the SQL db. Since this site collection was devoid of title the groupprovider was nameless (see grm groupproviders.xlsx attached). Because of that Appit had nothing to reference to pull in the groups associated with the site collection.
 

Resolution

The fix here was to have the user go to Site Settings andgt Look and Feel andgt Title, Description and Logo and give the Site collection a Title and then run the registration wizard. After doing this the issue for them was resolved.

For further information on the topic:

http://community.k2.com/t5/K2-Appit/Groups-Not-Appearing/ta-p/76173