Polished stone (from ExtraUtilities2)-Bits are most of the time (sometimes some of them work fine) invisible allowing you to see the caves (the thing that happens if a solid block has a transparent texture). I tested this at two diffrent days, with and without Optifine and with multiple restarts and texture-reloads.

Here one side of the block shows the texture, the other doesn't. Both sides are Polished Stone (a third side stone bricks).

This should be mostly polished stone....

Sorry for my english, it isn't my native language ;)

Which version are you using?

I can only reproduce a single issue with grass, in that the bit when holding shift renders as white, other wise grass seems to render fine in all cases.

I can reproduce the issue with Polished stone, but it will need some further research to see if I can solve it.

And one time a chiseld grass block went completely black. I wasn't able to reproduce it. Also chiseld grass has white grass on top when it is in the inventory and the shift key is pressed (to show the whole block)

Im using this modpack... Last time I checked, curse didn't show any updates. I can look up the version later...

I'm using chiselandbits-8.7 and forge-11.15.1.1808.

Strange, that is the latest version, i'm not sure why your getting white grass in the world... Which biome is it inside of?

The white grass is in the inventory.
In the world the complete block went black. But that was with Optifine and could not be reproduced with or without Optifine

Hmm, ok, so maybe its the same issue that I could reproduce.

"Something" is weird with the XU2 block models.. I don't know what.. but its something...

In other news I've simplified the model fall back plan in C&B which should resolve this in the next build.

Included in latest build.