Sharing a playlist via API produces unexpected behavior

When I share a playlist (example below) via shotugun API, associated note submissions hang on `submitting...`
```
def sharePlaylist(sg, playlistID, clientID):
  filters = [ ['playlist', 'is', {'type': 'Playlist', 'id': playlistID}] ]
  fields = ['playlist', 'user']
  share = sg.find_one('PlaylistShare', filters, fields)
  if not share:
    data = {'playlist': {'type': 'Playlist', 'id': playlistID}, 'user': {'id': clientID, 'type': 'ClientUser'}}
    fields = ['playlist', 'user']
    return sg.create('PlaylistShare', data, fields)
  else:
    return share
```
@pboucher explained this is not supported in the API. Can we get support for this? Perhaps I'm simply missing something in my code above?