Setting rank to 'P' or 'S' leaves the rank ingame empty

[thedexterbear]

Setting the rank to P or S on any level doesnt change the rank to P (or S), but resets the rank so that it is empty. Any other rank works, just not P or S. I had to restart my game and had just gotten S rank on the first level, and tried setting it to P or S*(again) but it made the rank empty. However, setting it to A instead made my rank S again. I have tried setting it to S on every level, it doesnt work.