Minecraft version: 1.12.2
Forge version: 14.23.5.2836
Ambient Environment version: 1.0.1

Issue:

When installed with mods like More Overlays or NEI and their Light Level Overlay is activated with a light source present the Overlay gets greyed out and looses a portion of it's functionality. Removing Ambient Environment fixed the issue.

Issue was noticed at day and night on the surface of the world and happened with a few different modded light sources including Silent's Gems Glowing Roses.

I can't seem to reproduce.

working fine with NEI

And working fine with Light Level Overlay