I tried to play with multiple shaders, however, Sildur's shaders don't work with OptiFabric, I just get a black screen.
I've tested it in regular Optifine too, and it works as expected there.

I've tested both Sildur's Enhanched Default and Sildur's Vibrant Shaders

Works perfectly for me, are you using any other mods?

Nope, I'm not using any other mods

Has this been resolved with the newest OptiFine version? It came with some fixes especially for Sildur's things