Version - 1.18.2
Fabric - 0.14.9
Mod version - 1.4.4
I am using the latest version available

I changed dark katana's parent:weaponAttribute parameter to one-handed(sickle), in singleplayer it works well, but in multiplayer (both LAN and server) the animation is broken. In local server my animation works as it should, but my friend's is broken. From my side I see him holding two katanas with default animation (which shouldn't be). From his side he sees default animation and one katana (while holding second in offhand) while attacking and sees me holding one katana with animation like when I'm using two weapons.
In normal server the situation almost the same (see videos).
I tried lots of weapons with changed attribute, and all of them don't work as they should.

Steps to reproduce the behavior:

1. Go to multiplayer with someone
2. Use the command /give @p mcdw:sword_dark_katana{weapon_attributes:'{"parent":"bettercombat:sickle"}'} 2
3. Take katanas in both hands
4. Attack
5. Ask your friend to watch it
6. See first error from friend's side
7. Ask friend to attack with these katanas
8. See second error from your side

Expected behavior
The animation should work the same for every player in multiplayer(sadly it doesn't)

Additional context
Trying to make a recipe to change the animation of a weapon using CraftTweaker.

local multiplayer
What should be

How I see my friend

How my friend sees me

On server

Me

My friend

Me again

It turns out NBT data is not synchronised to other players.
This is an issue of Minecraft itself. I am not sure how to fix it.

It turns out NBT data is not synchronised to other players. This is an issue of Minecraft itself. I am not sure how to fix it.

Oof thats sad. Any chance it's going to be fixed someday?

I guess there is always a chance. :D I will be looking for solutions, but it might not get fixed very soon.

I guess there is always a chance. :D I will be looking for solutions, but it might not get fixed very soon.

Anyway, I'll try to solve this myself, have some ideas how to fix this