Slopes with selected rail bed show empty spaces on level-change walls, as on screenshots below.
If this information is needed - yes, I use Optifine.

Hello, please try this without Optifine. Many mods DO NOT support Optifine and IR is one of them.

I could do this but I play on laptop, so without Optifine I would have low FPS, especially if there is a lot of tracks and about 100 villagers in loaded area :)
Or maybe is there other optimalisation mod compatible with IR?
Anyway, thanks for help :)

I checked it without Optifine, and this bug still exist.