The loot tables show minecraft:air where most clusters have their respective gems, and in-game they lack a recipe and drops.

Found the issue, I had incorrectly generated the data while the relevant mods were not present, so the items were missing and therefore defaulted to "minecraft:air".
I hope to get a new version out within the coming days.

I need a lot more info to help you.

• Which Minecraft version?
• Which Forge version?
• Which BuddingCrystals version?
• Do you have Mekanism installed? If yes, which version?

At this point, the only guess I have is that you don't have Mekanism installed, which would mean that both the recipe and the loot table are intentionally disabled to prevent issues.

Minecraft 1.19.2, Forge 43.2.3, BuddingCrystals-2.1.0, and Mekanism-1.19.2-10.3.5.473 (plus mekanism generators, but not the whole set of mekanism mods). I also don't have applied energistics, if that matters.

The loot table is at least partially working, because the buds and clusters drop themselves when silk touched.

I haven't updated Mekanism particularly recently, so it might be that budding crystals thinks it isn't there?

I'm using datapacks as a workaround for now, so I'm mostly saying this in case someone else ends up with the same or a similar problem.

Thank you for the details, I'll have to look into this. It's possible that Mekanism changed the internal name of the item, which I missed. I doubt the issue is in the detection of the presence of Mekanism though.