@elturbo
Hi Recalbox 8 has known issues with pi3B, B+. Most known issue is Retroarch freezing in game. You can find some topics relating on this on the forum.
https://forum.recalbox.com/topic/26323/recalbox-8-x-sur-pi3
The dev team is working hard on it. A new version will be released soon.

That said, i decided to get back to version 7.x, most stables ones so far on our system.

I hope it can help.