hi.
I'm running this mod(0.45.2) on 1.16.5-forge36.1.0, optifine G8 ,and using Sildur 1.283lite shader. I met an error while driving a vehicle and after some tremble with car (caused by terrain) then some textures of blocks lost (then i can see the void underground directly)... after break the vehicle, everything goes normal. I really don't know what caused this.
by the way, my forge version is which the forge officially recommended. and my graphic card is ATI RX560d(the manufactor sayid so, but software detected RX560 series.)
Hope you can reply me after you seen this, whatever you understanded the context. cuz my english isn't good enough. I'll try to make things clear.
thanks.

The problem is optifine, as long as textures are lost.My English either but ... I can help you with something.