Epic - High - medium - render inconsistency

Hello,
I was Playing with the Day sequence device (fog, clouds, moon) in medium setting.
I was happy but Epic and High scalability settings completly destroyed it ( I was in medium).

How to have the same atmosphere in all settings ?

-----Medium-----

-----High------

-----Epic------

------------------EDIT--------------------------
Lumen seems to be broken with fog :

Lumen is off when in Medium/Low setting, If you’re using High/Epic Lumen is ON