Maybe, if you tried to capture any of this emulator games you probadly had just black box. And here's your solution. In PPSSPP setting change your backend to anything, BUT NOT Vulkan, only cause of it you can't record it normally. After doing this, reset source in OBS, in PPSSPP go to settings again ( just go, don't do anything ) and now it works. I didn't find any solutions in the net, so it is probadly gonna be useful for runners.