Can't load Mario Mashup world.

I used to be able to enter my worlds just fine. But when I downloaded an update, the game won't let me go into my Mario Mashup worlds. When I click the world, a screen pops up saying "There was a problem loading this world." I've checked other questions and they say they downloaded the latest update and solved the issue, but it's still not working for me. I can still join my other worlds and make more Mario Mashup worlds.