I have found the same problem as this guy:
https://forums.libretro.com/t/trying-to-sync-saved-states-between-pc-and-android/
Even though I’m running the same core version on PC and Android.
If i try to load states saved on the Android device on my pc: The game flashes a single frame of the state, and a beep from the audio, then the Rom restarts.
It works fine for all other systems/cores.
I’m more surprised about this fact.
Most likely it is an issue about 32/64 bits having different sizes for their pointers. Hopefully that’s fixable, it’ll break backward savestates compatibility though.
If you wanna get this issue solved, you should open it in the right place : https://github.com/libretro/Genesis-Plus-GX/issues . Most core developpers don’t wander on the libretro forums.