Friends can’t join a former realm world

I’ve had a realm for a while now, but recently decided to cancel the subscription. I had saved the world that the realm was in and I can play that in single player. However, when I want a friend to join the world, it doesn’t show up on their screen. I’ve also tried inviting them to no avail. To be clear, they can join other, non-former realm worlds, just not this one. I’ve even tried making a copy of the world and seeing if that’s worked, but it didn’t. Also, (I think) by default, realm worlds have multiplayer off, but I’d turned it on days earlier, as shown in the screenshot. Hopefully this gets fixed soon!