Hi,
I have checked the scene.
The issue seems to be in CoronaSelect map, as the one used in your scene simply cannot have 0th map selected (any other than Map 1), even when done manually - it switched back to Map 1, which is black color.
Interestingly, newly created CoronaSelect maps work fine.
Workarounds are using Sky map as Map 1 in CoronaSelect map (Environment) or creating new ones, if that fits.
This is reported now and I will definitely keep you posted when this gets fixed.
Thanks for reporting it.
(Report ID=CMAX-1737)