Minecraft: 1.16.5
Forge: 36.0.43
Gaia Dimension: 1.3.2
Client log: N/A

To Reproduce:

Place a beam in a top-slab like position (tested with stonebrick)
Place a second beam in the same block in the lower position (so like a stair block missing the middle part)
Describe the bug
When placed in this configuration the top beam drops so the two beams appear as a bottom slab, and the face where the top beam was becomes an x-ray glitch

Note: I discovered this on the tf testing server and put it in the wrong github because I'm a potato