blocks that are supposed to be waxed are weathering

What I expected to happen was...:
2 waxed lightly weathered cut copper slab become a waxed lightly copper block

What actually happened was...:
Block created from two slabs is reverting to non waxed type

Steps to Reproduce:
1. in creative mode
2. place 2 waxed lightly cut weathered copper slabs on top of each other 
3. block will act like regular copper block and will patina