For the past couple of days I’ve been playing Super Metroid. In a section of the game, i need to dash left and jump (hold D-pad Left and B ,tap A). The problem is that I can’t manage to do it. If I press D-pad Left and B, hitting A will do nothing. Odd thing is that when I try to do the exact same thing with D-pad Right it works perfectly. I am using bsnes-mercury core and a keyboard for input.
Sounds like you’re hitting a key rollover issue.
Do you see the same behavior in Windows’ game controller properties?
RetroArch has a number of joypad drivers you could swap between (xinput, dinput, sdl2, hid) so it may be worth some experimenting with that.