What Happened:
Using repeating command to teleport an item that was drop from player to a location doesn't render that item to the correct location until either action listed below happened.

• The hitbox of this item touch another solid block.
• Just wait for couple seconds...

What I expect:
The item that is constantly been teleport should render its' location correct right away.

Command used in 1.12.2:

execute @p ~ ~ ~ teleport @e[type=item] ~3 ~1 ~

In 18w03b, or 1.13-pre5:

execute as @p at @s run teleport @e[type=item] ~3 ~1 ~

20180703185019.gif (Recorded in 1.13-pre5) shows a white line (area_effect_cloud) that represent the location where the item would be teleport to. However the drop item(command_block) wasn't rendered in the correct location, until approximately 5 seconds.

1.png shows the drop item is render at the location where the item first appear in the first couple second. 2.png shows the correct render location after approximately 5 seconds.

And 3.png shows the item is touching the tripwire(not a solid block), thus redstone signal was created. But again, the item doesn't render at that location until after a while.

This would not happen if the drop item was on the ground before the command was activate.
Also happen in 1.10.2, 1.11.2 and 1.13 snapshot other than pre-release, but seems like I don't have the choice for adding those to Affect version...

To recreate:

1. Place an Always Active, Unconditional, Repeat command block.
2. Enter this command below into that command block.(I am the only one in the world, so @a or @p doesn't matter...Singleplayer Mode)

   execute @p ~ ~ ~ teleport @e[type=item] ~3 ~1 ~

   or this if you are in 1.13-pre5

   execute as @p at @s run teleport @e[type=item] ~3 ~1 ~

3. For better observation. Run this chain command(corresponding to your version) after the command above.

   entitydata @e[type=item] {NoGravity:1b,Age:-32768}

   execute as @e[type=item] run data merge entity @s {NoGravity:1b,Age:-32768}

4. For visualization of the correct location, repeat the following command and press F3+B to enable hitboxes. (corresponding to your version)

   execute @p ~ ~ ~ summon minecraft:area_effect_cloud ~3 ~1 ~ {Duration:0}

   execute as @p at @s run summon area_effect_cloud ~3 ~1 ~ {Duration:0}

5. Make sure the location ~3 ~1 ~(where the item should be teleport to) doesn't have any solid block
6. Drop an item either dragging it out from your inventory or press Q when the item is in your main hand.