I found a hidden file causing this issue. I couldn't delete it so I deleted the Megadrive folder itself and recreated the folder.
Also if you have a Mac and use Finder you may end up with lots of files starting with ._ To get rid of them use the dot_clean comman in Finder. Link here https://lifehacker.com/delete-mac-system-files-with-dot_clean-377011
Did you get this working? I have exactly the same problem. If anyone can help it would be greatly appreciated.
I've just given my daughter an IPS RG300 and she'd love to play Sonic! She hates the stock gmenu system. Thanks.
I have recently purchased a Retrogame RS97 HW version 3 and installed RetroFW and Pymenu, all works great but im having issues with one system.... megadrive, when i add my rom location folder i save the settings, go into that system and can see all the roms from that rom folder location, i execute one, which runs correctly...as soon as i exit the list of roms has dissappeared.
I check the rom folder location and its correct, the only way i can fix this is by setting the rom folder to something else, then back to the correct location and the roms reappear as soon as i back out and go back into the system they are gone again and have to repeat the process.
Has anybody else seen this?
I have even created a duplicate megadrive system in pymenu and it does the exact same.