Cut copper slabs behave differently from the other slabs.

On the screenshot below, you can see where I was aiming to place a cut copper slab and where it was actually placed.

And this is how other slabs behave: when aiming on the top part of a block, after placed, it occupies the top part.

In my observation, the only way to place a copper slab like the smooth stone slab on the picture above, is to start with setup like the one on the picture 1 and simply click again:

This is what happens if I repeat the same process as shown on the previous screenshot, but with a smooth stone slab:

And here is another example, cross shows where I was aiming at while placing cut copper slab:

Repeating the same process, but with a smooth stone one:

So, this is clearly a bug. It made my project pretty much impossible to build. Thank you for your time.