Yes i have tried that, i have tried everything. Reinstalling OBS, CSGO and i have most likely watched every online tutorialI personally would say 2500-2750 bitrate. Set your x264 CPU Preset to Faster instead of Very Fast.
Now the black screen issue. I have no idea. The game capture seems to be catching the game okay. Have you tried deleting the game capture source and remaking it to see if that works?