Bring back the ability of a public account to join a group created by an organization, and allow an organization account to join a public group. This all worked just fine before it was changed with the March update.
This idea has been merged with Allow a public user to join a private group authorized by Organization Administrator.
How does ESRI expect people to share data and maps if we can't do something as simple as join a group? This doesn't have to be a private thing, just allow the two accounts to join groups created by each other.