find out savestate version

[vsub_]

On the left side you see the normal saves names.
Remember the first 9 characters of the name and check if you have a save state in the PPSSPP_STATE folder that start with that name(9 characters)

If you don't see such save state,then that means you don't have save state for the same version as the save

Also you can try tuning the program as administrator(I'm not sure if it's needed)
Btw if you can't see the states in the program no matter what you try,open the save state you want with some hex editor and if you don't see the ppsspp version at the top(of course the hex editor must also show strings\text,not just digits),search for v0.