changing Motion:[X, Y, Z] tag on projectiles don't change the motion only server side, resulting in the projectile visually teleporting regularly on previous locations, or not moving at all. this is problematic for datapacks makers when you want to do a weapon that throw custom projectiles, you have to change the motion of the projectile after summoning it with a /data store entity
step to reproduce:
summon a falling_sand with no motion, then change it to something else, visually it will fall right down, but when hitting the ground the sand block will teleport onto the location where it really landed.
probably related to MC-128812
Linked issues
Comments 4
Duplicate of MC-127456.
Resolved both as dupe of MC-99442.
This may have been resolved for projectiles, but still affects falling_block entities in 1.16.5 and 21w20a. It's more "slow to update client-side" than "doesn't update at all," but still a noticeable issue. If that's already been reported somewhere else, I can't find it for the life of me.
Confirmed for 18w46a, without modifying the data with commands. Slime blocks being pushed by pistons can set a falling block's motion to 1.0d, which will desync the falling block.