This seems to be a consistent problem with the Mac version at least. If I have the IR running, at some point it will crash, but it seems like it’s during different actions each time. This time, I was adjusting a deformer’s settings when the crash occurred, but it happens all the time when the IR is running. I have a ZIP ready to upload.
Scene and crash reports uploaded.
Thanks for uploading the scene and reports. That’s one less thing we need to ask from you! 
I have also some issues when IR is running.
One thing I found: Just click three times on the visibly in render button of the Crash object while running IR.
When the instance is on “Instance” or “Multi Instance” everything works fine. But it always crashed when it is on “Render Instance”.
Nice weekend 
MacOS 10.14.4
R20
Version: 4.0 daily Apr 16 2019
