Blocks that were made pre 18.104.22.168 that used custom geometry no longer have textures applied properly, I assume this is a bug relating to either the material instances or geometry component as all other custom block features still work.
Steps to Reproduce:
- Download supplied pack
- Give yourself the custom slab
- It won't have a texture
- Custom Blocks use textures and geometry defined in geometry and material_instances components
- Blocks display 'update texture' texture