Unfortunately I didn't find anything helpful. I could find the posts where players said they were unable to relocate but no later response on whether their issue was resolved.

I see you did open a bug report so that's one step out of the way.

Until you get a response on that, all we can do is try to narrow things down.

Is the character that owns the house that you're trying to relocate still in a FC? If so, remove them from the FC. I know you said you did that with your alts but I'm not certain you did it with the house owner. It's better to make sure that the only house on that world your characters on that world have access to is the one you're trying to relocate.

With that in mind, are any of your characters on that world tenants in houses owned by other players? It's a bit of a stretch but there's always the chance that's causing some sort of error.

Otherwise, I'm at a loss. We know it's okay to purchase multiple personal houses as long as each house is on a different world so what you have on other worlds shouldn't have any impact. I can only hope they get back to you quickly about your bug report.