Thanks, is it the static light or the real light that shines on the ground? If it's the real light, go into your advanced graphic settings and set light quality to very high or ultra and apply that. If it's the statics I would say it's a conflict and check your log in the farm sim folder for errors. There's a lot of bad conversions out there causing problems.
If you can try it in a folder by itself or with minimal mods and see if it works fine. Then add mods back till you see the issue appear to help figure out what's causing it. Only issue we've seen so far is the real lights on the ground and that setting fixes that. If you're on the facebook page you can message me directly for a quicker response.
Derek