Summary:

When trying to place copper slabs on a full bock they either go to the bottom half or out to an air block. To put it on the upper half you have to have it surrounded with no other options 

Steps to Reproduce:

1. Make cut copper slabs.
2. Place on your build against the upper half of a full block. .

Observed results:

They don’t place correctly, usually will just go to the bottom half. .

Expected results:

slabs are placed against the top half of the block.