What actually happened was...:
After coming back from nether, already placed torches weren't producing any light. It was night so I went to bed and when I woke up large sections of the chunk I was in were pitch black and monsters were able to spawn even in the light areas (and weren't burning from the sun) despite it being the middle of the day and the ground being covered in torches. The new torches I placed lit up the area like I was in a cave and didn't fix the visual lighting issue like it normally does when there are light bugs.

Steps to Reproduce:
1. Go to nether.
2. Return through nether portal at night.
3. Go to bed.