Very closely related to MC-4. I initially misinterpreted the updated reproduction steps to think that MC-4 was describing this issue, but later realized that this issue is distinct.

The bug

When using a repeating command block to teleport certain entities to a certain location, their positions on the client side will almost never be correct. They will constantly snap back to the expected position every two seconds or so, but will not remain there.

From my testing, the following entities are affected:

• minecraft:item
• minecraft:experience_orb
• minecraft:egg
• minecraft:snowball
• minecraft:ender_pearl
• minecraft:potion
• minecraft:experience_bottle
• minecraft:small_fireball
• minecraft:fireball
• minecraft:dragon_fireball
• minecraft:eye_of_ender

How to reproduce

1. Obtain a repeating command block
2. Insert the following command into the repeating command block, substituting entityidgoeshere with one of the entities listed above: tp @e[type=minecraft:entityidgoeshere] ~ ~2 ~
3. Activate the command block
4. Bring some of that entity into existence via your preferred method

Expected results

The entities teleported by the command block would appear frozen above it for as long as the command block recieves power.

Actual results

The entities are instead periodically teleported above the command block before moving elsewhere, such as shooting off in their prior trajectory or falling onto the command block. This appears to be in rendering only.