Can't Join Multiplayer Game (Purchased Game on Two Separate Accounts)

[ChillWill86]

I have two Xboxs in the house, and my son and I play Grounded 2 on two accounts.  Because of some of the tech issues, I just ponied up and purchased the Founder's Edition on each account for each Xbox.

We're trying to fight Axl this weekend.  

We use my son's account to host the multiplayer game.  And I can log into the game from his account.

But when I go into Grounded 2 from my account, I can't join his multiplayer game.  When I try from the Grounded 2 "Multiplayer>Join Online Game" prompts, I don't see any "Games Hosted by Friends"; even though my son and I are friends on Xbox

When I try to go through the Xbox Main Menu and use "People>Friends>Join Game" option, I can see that he's in the game.  However, when I try to join the game, I get "Join Game Failure/There was a problem joining the game/Network Incompatible" error.

I bought the game twice to try to avoid these issues.  Any ideas?