There is a 'Missing' Texture in the SSS of the inventory

I had a Super Secret Setting on, and I had stairs in my Hotbar (screenshot) and the top part of the stairs had no side texture. It doesn't look like this in the creative inventory, only in hotbar or survival inventory

Is Duplicated By
1. Put on any Super Secret Setting
2. Place any stair in Hotbar
3. and look at the preview