Some block state model files mismatch with their counterparts in the saved metadata. For example, these blocks have undefined states in the model files:

• Cactus/sugar cane: growth stages
• Jukebox: "has_record" state
• Bed: "occupied" state (see MC-106065)
• Hopper: "enabled" state
• Dispenser/dropper/etc.: "triggered" state
• Dirt and Coarse Dirt: "snowy" state ^{Removed in 1.13}
• TNT: explosion state ^{Removed in 1.13}
• Melon/Pumpkin Stem: combinations of growth and rotation ^{Removed in 1.13}

Basically, any block that has the "variant" (or color) state is split. This is in contrast to other similar blocks (flower_pot) which condense the variants into one file.

Workaround: Using multipart allows access to all block states. However, multipart should not have to be used for states that should be defined variants.