I am having trouble explaining this, because I have nothing to do with coding/modding so please bare with me :)

I made a modpack. And got a dedicated server from Kinetic.
It includes (among other mods) Immersive Weathering, Panda's Falling Trees and Treechop.
Here's a screenshot of what happens and I'll detail the steps below.
https://i.postimg.cc/j2fpTsJH/2024-12-18-16-30-41.png

1. I chop the tree. Using Jade, I see it reaching the 5/5 logs breaking, dropping 7 logs.
2. Tree "fells". Sometimes, the chopped log retains a slim state. Sometimes (eg. screenshot) disappears. Sometimes (if tree is very tall) a good portion of trunk disappears. But always the tree top (logs + leaves) remain like in the screenshot.
3. Log items drop as intended.
4. Saplings drop.
5. Immersive Withering does its thing, leaving leaf piles on the ground, that break when hit, dropping more sticks/saplings.
6. The "remaining" logs/leaves remain solid, respawn instantly if you try to break and disappear after relog. If I cut the tree and create this "encounter", all online players see it the same. And each player must relog in order to "remove" it. As in if I relog, I remove it only on my screen.
7. The "remaining" logs/leaves can be deleted with right-click, but again, only on your screen.

None of this happen on singleplayer. Same mods, same config since the modpack is made by me, uploaded by me.

Kinetic support said "A mod working on singleplayer, doesn't always mean it will work on the server".
I don't know what to do. I want to keep the mod because we love the visuals of it and the fact that it works with all trees.

Update.
We added ESSENTIAL and I hosted a world.
Me, as the host, saw the tree falling as intended. Same thing as in singleplayer. Even if was cut by me OR by my friends.
Them on the other hand, saw the tree as described in the original post. Even if it was cut by themselves or by other player.

So what I understand is that server/host isn't sending the block state(?) to client...?

#185 seem to solve my issue.
But maybe this post would help other noobs like me find the solution, since this one has more words than issue185 :D