Just a heads up, I may have figured out a bit of a solution to this.
I'm a pretty stubborn macOS streamer and even though there's dozens of issues with OBS I always try and power through them since I'm locked into the platform and enjoy streaming whenever I can.
Every since updating the Mojave I've had to redo some of my stream setups (SyphonInject is currently broken in Mojave with no real solution in sight). In the process of switching over my GameCaptures to DisplayCaptures (Cropped to windows) I noticed quite a bit of seemingly random "screen flickering". (Example here:
https://clips.twitch.tv/FunnyOpenEggnogSeemsGood). Not really often enough to be completely unwatchable, but just often enough to be incredibly frustrating.
Determined to figure out what exactly was causing the issue, I decided to start a process of trial and error. I began by watching the scene preview in OBS and tracking the flickering, I then removed every element in the scene other than the elements experiencing the flickering. When isolated by themselves there was no flickering occurring, which means something else in the scene must be causing it. Long story short, I went through all the elements in my scene, turning them off, watching for flickering, then turning them on again. I've come to the conclusion that any Window Capture elements active in the scene will interfere with any Display Capture (Cropped to window) elements, causing the Display Capture elements to flicker. Most people don't use Window Capture on macOS anyway since it's incredibly laggy, but I had been using it for a few static widgets in my scenes and never noticed any issues. After converting the few Window Capture elements I had to Display Capture I haven't noticed any screen flickering issues (fingers crossed). Hopefully this will help other people experiencing the very frustrating issue.
TL,DR: If you have a scene with both
Display Capture (Cropped) sources AND
Window Capture sources, the Window Capture sources will cause the Display Capture (Cropped) sources to experience random flickering. The solution is to remove the Window Capture sources or convert them to Display Capture instead.
