I didn’t even know that it was playable until one of my students showed it to me today. It is not selectable at all. It looks like I need to complete a level to activate it, but I have completed all the available levels.
Have you done Drop the Flag in the forest? Currently that level unlocks all three multiplayer arenas.
Yup, I went ahead and did it again in case that was the issue. No luck.
Ah, actually I misspoke–it was Rich Forager that was supposed to unlock those. And it looks like it was misconfigured. I have added the achievements to Rich Forager, so try getting that one complete again and see if they unlock then.
That did it! Thanks!