Thank you for your investigation. I will take a closer look and send fix this as soon as possible
Meanwhile, please tell me:
Which version of UE4 do you use?
Do you have the same warning on Fast Stylized Procedural Sky example map?
Currently, I can’t reproduce this problem that makes this warn harder to fix.
Could you try to change “SkyUpperColor” back to “replicated” and check if warning still exist?