Blocks with custom geometry do not render correctly in inventory. Instead of rendering as they would appear elsewhere with the same geometry, the appearance of cubes seems to be essentially based on render order, causing the inventory model to appear garbled, with random faces that one would expect to be visible not visible, and vise versa.

Custom blocks use the material ui_item to render in inventory, which is the same as all items and blocks excluding those with glint, which have a separate material. Whatever depth testing this material and its associated shader are doing seems to be simply insufficient to render anything with complex geometry.

Reproduction:
1. Download and install the attached addon.
2. Create a world with the attached addon (being sure to enable both the associated resource and behavior packs), enabling Holiday Creator Features.
3. Give the block contained within the addon to the player via:

give @p geysercmd:gmdl_1

4. Observe that the inventory model for this block renders improperly when compared with the in hand attachable using the same geometry.