Uhhm idk, I wrote this few months ago, it worked (and still working) for me in the Retroid Pocket 2+. For this handheld, the factory default and recommended GC Emu is MMJR2 for performance reasons (in MMJR2 you can set half res, quarter res, etc.), this has been talked many times in different forums, YouTubers and guides.
Hope it helps to understand the reason of why a wrote this few months ago, my intention was to help people that had the same issue but is also true that could be a very specific case (RP2+)
Thx.