I just recreated that setup and was unable to get that crash. So hopefully that means it is fixed already in code.
I am not exactly sure how you are using pixel depth offset to fix the floating blend. That may just make both layers have pixel depth offset that is correct in-and-of-themselves, but I can’t see it fixing the floating blend. But I am interested to hear your solution since I have been thinking of making a separate version of the POM node that is intended to work with multiple layers.
The method that I thought of to make work nicely involves passing a ‘mask’ texture object input into the POM node but it would involve a double-texture lookup at every loop iteration and wouldn’t easily work on landscape since you cannot sample the blending mask at offset locations.