I've run into a strange lighting issue and I haven't been able to find anything similar in the questions so far, but please let me know if it's a repeat.
Firstly, following the lighting tutorial as best I can, I've got a CanvasModulate and several Light2D in Mix mode in a scene in order to get the look you see here:
Which works fine by itself.
My main game scene then displays that scene within a Viewport in order to maintain specific pixel perfect scaling as well as paste a GUI on top of it.
The issue is that the background image I'm using to fill space around the Viewport is showing through where the lights are and I'm not sure what's causing it. It's probably just a setting I'm missing or something I don't understand about the way Viewports or Light2Ds work.
Any help would be greatly appreciated! Thanks in advance!