Work at a Pizza Place Xbox players can no longer play with mobile and PC players since my last Halloween update on Sunday.
A new place was added to the universe in that update so that is most likely the culprit: https://www.roblox.com/games/2521233669/Maze-of-Terror
I used my alternate account on my Xbox one and my main account on my PC to enter Pizza Place. The accounts were not able to join the same server together when they pressed “Play”. My alternate account ended up in a server with only other Xbox players. However, if one of the accounts manually joins the other, the accounts are able join the same server together.
Mobile and PC accounts were able to join together automatically after pressing play. It seems to me as though matchmaking is automatically grouping mobile players with other mobile players and PC players with other PC only if they do not have a friend already playing the game already.
(In case it is relevant: I use TeleportToPrivateServer to teleport players to the new universe place. Seems to work fine for every platform.)