What controller are you using for the MiSTer? Currently I am using a Dual Shock 4 with the 8bitdo brick bluetooth adapter and pretty much all of the cores control fine, although I realized today that the Atari 5200 core is giving me problems with moving left or right. This is a newer issue.
I just purchased a new bluetooth adapter because the new update allows three or four controllers to be controlled by one bluetooth adapter instead of the 8bitdo adapter that only syncs with one controller at a time. After I get the new adapter I will test the 5200 again and see if that fixes my issue.
The 8bitdo SN30 Pro, works decent. BT feels out of the question, quite laggy from times to time. Only using it wired.
Thing is I wanna have the option to play with the original controller. If I cant, the zero-lag-100% accuracy aint worth it.
The MiSTer needs controller adapters for original controllers, connected to the serial I/O.