Before I post a bug report, I’d like to know if any other Mac developers have experienced this. When we moved to 4.20, we began to hang our computers when loading or playing levels in the editor. This was a very hard hang (or crash, it happens both ways). It turned out both levels we had problems with happened to have a lot of objects or had complex lighting builds. By switching to Metal 1.2 shaders, the hangs and crashes stopped. We could also stop them by removing a number of objects in the world.
One other factor of note was that OS X wasn’t hanging when it would just hang, you could ssh in, but the User Interface was gone.
It would reboot the computer sometimes and that would allow us to see the system log. It appears that 4.20 with Metal 2.0 was trigging some bug in the video drivers. We had this happen with two Mac Pros, 32G, dual 700 video cards (the trashcan style macs). The machines would also both show the symptom of the fans spinning up (if you know the trashcans, they don’t tend to get the fans going often). I don’t think this is a UE4 bug as much as 4.20 just using the Metal 2.0 shaders.
I am curious if anyone else has experienced this.