Okay, so this might be a bug in version 4.12.4 . I tested it multiple times and I can confirm that this is a bug: Create a BP, and create a child BP based on the first one. When you try to enable “Render Custom Depth” in the child one, the editor crashes. Works okay, when enabling in the parent one.
I haven’t been able to reproduce this in 4.12.5 or 4.13.0. I’d recommend upgrading the project to one of those versions, as this is most likely an issue that was fixed in a later version.
Let me know if you have any further questions.
Have a great day