Was just getting a ton of lock ups all around (mostly in Metal Slug and Dolphin Blue and Faster than speed), with a Genuine GDEMU.
I updated to latest firmware for it, and still was having problems.
Tried different SD Cards and switch from different adapters to full sized SD Cards.
I also noticed the madsheep 1.10 was inputting its own settings into the gdemu.ini
So i editted the GDEMU.ini file on the root of one of my SD Cards (Sandisk Extreme 128GB)
These settings helped me to be able to beat Metal Slug 6. Would always lock up in level 1, or 2.
Maybe it will help other people experiencing the same issue or maybe its a coincidence, but i haven't had any issues since.
open_time = 500
detect_time = 250
reset_goto = 1
image_tests = 0
read_limit = 0
These settings still lock up for me on my Micro SD -> SD Adapter per the instructions for this game, but the full size SD card does work correctly now.