I think I've found the issue with those infinite loops. In each of the C# files for those effects, in the Create method near the bottom, you'll see I'm changing the name variable? Comment out that line and see if the infinite loop is gone.
Unity seems to not like having parentheses in the name, so I think what's happening is: the shader gets added to the Renderer Features list, Create is triggered and the name is updated. Unity sees the invalid name and removes the parentheses. This triggers the Create method (for whatever reason, any change to the variables in-Editor seem to trigger Create), so the name gets changed, so Unity removes the parentheses, so Create is triggered, and so on.
Note, I'm working with 2019.3.15f1 now and the latest URP. Seems that "Before Rendering Post Processing" messes with the Scene View, and "After Rendering Post Processing" works again. I'll include information regarding this in the next update's documentation.
Thanks for your patience on this!