Blocks with custom Block Dimensions glitch when player colides

It only happens when you edit the X or Z coord, so you can walk ''inside'' of the block. When you ''walk'' inside the block, it shows you the texture of the block and pushes you  out.

If you edit the Y coord so your block is smaller (like a slab, for example), nothing of that happens. I haven't tried what happens if you edit the Y coord so the player head can be ''inside'' of the block.