Weird deadzone on analog stick.

[Nightquaker]

Hello there :3
I have an issue with PPSSPP and analog stick in games.
There is a weird deadzone on diagonal left-up direction of analog stick that cuts the analog range, breaking movement in games. It's not an issue with controller itself as I just checked it for deadzones and everything is working fine. Has that issue occured with anyone else and is there a fix for it?
I'm using Logitech F510 controller in XInput mode, switching to DirectInput doesn't solve the problem.
I'm using PPSSPP 0.9.9-2, but that issue also happened in previous builds.