DISCLAIMER: I have been playing this mod with a bunch of other mods, including Blooming Biosphere, Cobblemon, FallingTree, and some others. I highly, highly doubt this is a compatibility problem/interaction, but if it turns out it doesn't happen with the mod by itself, I can tell you all the mods I have.

I've broken probably around 20 naturally spawning coconut trees on the latest Fabric version of this mod, trying to get coconut sprouts, and not a single sprout has ever dropped. Forgive me if I've just been unlucky, but I think something has gone wrong with the leaves' loot table here. It's worth noting that sticks drop from decaying coconut leaves just fine, it's just sprouts that seem unobtainable.

coconut sprouts dont drop from leaves, instead the coconut sprouts are obtained via bonemealing a coconut

oh oops sorry