When an arrow is summoned with motion copied from another arrow, the new arrow doesn't visually update for about 1-2 seconds (or until it hits something). Server-side functionality works as expected (dealing damage, etc)
Steps to reproduce:
1) Shoot an arrow
2) Summon a new arrow and copy the Motion data from the first arrow to the second arrow
3) Kill the original arrow4) Observe the new arrow fall to the ground for 1-2 seconds before being updated to its correct position
4) Observe the new arrow face the wrong direction temporarily until its rotation is corrected during flight (if the arrow hits a block quickly after being fired the rotation will not have time to update)
Download the attached datapack and shoot a crossbow to see this in effect.
Video demo: https://youtu.be/e1s2BCh8F2Y
Updated video demo: https://youtu.be/32UtDGqt8a8
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The bug with arrows only started occurring in 1.21.2 snapshots, it was not an issue in 1.21.1. But the bug you linked does appear to be similar yes.
It is also worth noting for those who are familiar with mapmaking techniques, air toggling fixes the arrow visual bug as seen in my video above.

Confirmed in 1.21.2-rc1

This was marked as fixed in 24w44a, but the issue is not completely resolved. Now when the arrow is summoned, it will be in the correct position but it will be facing south. The rotation is slowly corrected as the arrow flies through the air, but it can get stuck in a wall facing the wrong way if it lands quickly after being shot. I have linked a new video in the post showing this updated behavior.

Hey @unknown, the new rotation behaviour is as intended. If you want the arrow to spawn with the correct initial rotation, you need to set that rotation. The movement direction will slowly rotate the arrow, but the initial rotation will not be overwritten by the motion anymore. Hopefully this can be worked around and might even make more things possible as these are now decoupled.
Does MC-139548 describe your issue?