August 2018
I mastered all of my characters and now my rank is stuck at 53-70. Have been playing for three days now and it still hasn't changed. What might the problem be?
November 2018
The issue ended up being that I never bought the sticker pack with Unicorn chomper and Z7 Imp. So my rank stopped when all of my other characters where mastered. When game modes came out that I could play Unicorn chomper or the Z7 then my rank would move again. My rank is now 54/55 and I still don't have those characters, but was able to master them when they where around. Hope that helps someone else with the same problem.