If you email the save file to trundle707@gmail.com I can try taking a look. There isn't a maximum rank on monsters so I don't *think* that's the problem. A monster can level up their stats infinitely. It's just the picture / name that caps out at level 4.
Victory% should be taking into account who strikes first. Under the hood, the game is just running 5 simulations of combats to calculate the win chance so it's not a guaranteed win or loss when it shows 100% or 0%