Bought Minecraft on childs account on Xbox Series X, child is unable to play on other console

Yeah, the game doesn't require a subscription if it was purchased. Double check the transactions on your child's account at http://account.microsoft.com to make sure it shows the purchase on their accoubt. If it doesn't, then either the origibal purchase didn't go through or it was purchased on a different account.

Yeah, that sounds like the issue. It sounds like they were playing on the first console by accessing your Game Pass through the Home setting, which is why you didn't need to sign in there.

If the game was purchased within the past 14 days, you could submit a refund request. https://support.xbox.com/en-US/help/subscriptions-billing/buy-games-apps/refund-orders

Thought as much. Checked the purchase history, looks like I purchased Minecraft for Windows by accient.

Yes, the game is an online multiplayer so we need an Xbox Live Gold or Game Pass Ultimate to play it on our Xbox console. You may also confirm it on the Store page; https://www.xbox.com/en-US/games/store/minecraf.... It says there "Online multiplayer on console requires Xbox subscription (sold separately)".

Are you saying an active game pass subscription is needed to play the game in single player mode? I believe you are very mistaken.