Yes, you are right! Thanks! It partially works now. If I set the sunlight to stationary instead of moveable then it gets rid of the strange shading/lighting I was seeing. I still cannot use the “Ultra” shader or any of them that use SSR without getting strange in split screen, so now I use the one with Gerstner waves, Foam and Cubemap and it looks pretty good. Not as good as Ultra, but definitely better than the I had before. And I guess I will have a hard time including any of the weather or time of day if I want to later, but for now it is a big improvement already.
Cheers!