My experience is similar to TheHansen01, I can find “Anna Hop”, and other ‘red circle’ kits, in both MediaBay and Groove Agent SE and full Groove Agent 5. The kits currently load and play, but no way to track down where they came from (other than the indicated “Groove Agent One”) nor what .vstsound they are associated with (Steinberg Support hasn’t be able to figure this out either).
The way this has shown itself has changed over time, maybe as result of C13/MediaBay/GA updates. At one point the red circled kits wouldn’t play and there were also red circled instruments, MIDI, Styles in Groove Agent. As of latest C13/MediaBay and GA5/GASE5 (v5.2.0.30) the red circled kits load and play in both but there are no red circled instruments, MIDI, or Styles at the moment.