Searching for this setting yield only this issue on Github - https://github.com/libretro/RetroArch/issues/4820 - which seems to suggest that the setting does nothing and it's not implemented in the mame core.
Have you tried using save states (.stateX files) ? Does it work ?
@Silent_Gunner (a.k.a @NoBullShit) - you just registered again just to add more insult to the injury and pretend to provide 'helpful feedback' to your own posts. Looks like you've made your choice.