I experience the same problem since early version like 2 or 3, I have reported before and the problem seems to persist. In my case if I'm using IR lets say 1000x1000 px and the I wanna see some better details and change the res to something bigger, when I start again the IR after change the res it eventually crash, it's not all the time but happens very often. I'm also on Mac version Mojave 10.14.6 c4d R21.115