Day & Night Cycle - Sun Goes Down but Won't Come Back Up 4-26

Hey everyone, using UE 4.26

I am working on a Day/Night cycle and I am happy with all of it mostly except one major issue:

The sun sets as it should, but never comes back up. Once the sun sets, it is eternally dark.

Weirder still, is that when the Speed is set high, like 5 or 10 or 20, the sun DOES come back up. It is only when I lower the Speed to something more realistic (my goal is 0.5) that it stops coming back up.

Why is this happening? How can I fix this issue? Thanks!!!