Lights create occasional black streak flicker

I’m not sure what exactly to call this, but I’m using a global light to make the scene dark except for a 320px radius of the character. It sometimes has a black streak that lasts only a frame or 2, but is kind of distracting. It also seems to be random when it happens.

I thought it might be because of too many light obstacles being active, so I did what the wiki suggests and had it only activate the behavior when the character is within 350px of the light obstacle. That didn’t change anything. What would be considered “a lot of light obstacles”? I had to line the walls with 32x32 tiles as light obstacles, so at any given time, there are between 20 and 60 (just a guess) active light obstacles.

EDIT: I was able to figure out that the black streak is one of the light triangles flickering. The question remains though… how can I fix it?