I use an OTG cable too but I guess the difference could be that I use the official wired controller plugged directly into it? To sum up my issues: the triggers and right analog stick can't be used to map buttons to at all, and the left analog stick is forcefully used as the directional buttons even ...

Is there any chance of full Xbox 360 controller compatibility i.e. triggers and dpad? FPSE is the only emulator on my Android to not be able to map them so it's quite jarring.. thank you.