Crash w/ Structure Blocks

[WenXin20]

Minecraft v1.12.2
Forge v14.23.5.2838
EDX Multipart v1.1.1
McMultipart v2.5.3
Capsule v3.2.103

• If I add a double slab to a new structure file using the structure block, the game will crash when using structure blocks to place the new structure.
• EDX Multipart converts double slabs to McMultipart blocks, which seem to crash with Structure Blocks.
• This also means that McMultipart blocks are incompatible with the Capsule mod, as seen in the post I posted here: Incompatible w/ McMultipart Lythom/capsule#15

Crash Report