I got the same issue, the only solution is to go through all the open battles and try to find yours.My battles keep disappearing and i still have other players battles under the "my battles" tab and i cant find mine under "finished" or "my battles" so i can´t play when i have registered
It'll show the "Resume" button when you click on the correct battle.
Keep in mind that sometimes it takes a couple minutes for the list to refresh with your battle, specially if it's the Big Bass