Titan Games
well, it looks like it is more than a little problem...
when you click join, then game layout starts, but in preview, it doesn't know it is host at first, so it doesn't create a tank for you.
clicking the badges button restarts the game layout, and the second time it knows it is the host and does create the tank.
(I couldn't get a peer to stay connected, but that may require exporting... it has been a while since I played with multiplayer, so I don't know exactly what I am doing).
if you click the green CreateButton, it calls up the UI, but the tank is behind the spawn2 sprite so you cant see it. (you should move the tank, turret and tracks to the Creator layer.
You aren't picking any specific tank, so all players tanks would get moved to the spawn2 area...
then when you click the badges button to go back to the game, it is just restarting the game layout, which is resetting the whole game. So, you should be just hiding the Creator layer, moving the tank back to the game layer and putting it back where it was or at a spawn point...