Thanks for your report. I think I know what this is. You should also be able to work around this by loading another slot first, even if that slot does not contain a save state.
SNES Save State Test core
Re: SNES Save State Test core
Nice, that work around does indeed work! Definitely better than what my work around was. Looking forward to further updates!
Re: SNES Save State Test core
This is really cool! Tested it out and it seems to work great. Just wanted to note that this seemed to fix some other issues I was having with SA1 roms on the stable build. Thank you paulbnl