At first

I ’m Japanese and I do n’t know much English.
This report was created by machine translation (Google translation).
Please understand.

Summary of this bug

This bug occurs when teleporting is repeated at intervals of 1 game tick while riding on Minecart.
For example, execute as @e [type = minecart, limit = 1, sort = nearest] at @s positioned ~ ~ ~ run tp @s ~ ~ ~ 1 is written to the repeat command block in the spawn chunk and gets on Minecart. If you execute the command block, it will be read for a while, but after a while, the reading stops and the execution of the command block stops, making it impossible to move. Also, you will not be able to get off with a sneak key.
The integrated server on the debug screen averages 13ms and does not exceed 50ms.
If you run the teleport command on your own, it will become operational, but Minecart may disappear.
This bug did not occur in 1.13.2.

Quoted from a comment from Flashteens

I'm one of his coworkers on Minecraft map projects. Let me add some comments to the description:

1. The command he mentioned above should be revised as:
execute as @e[type=minecart,limit=1,sort=nearest] at @s positioned ~ ~ ~ run tp @s ~ ~ ~1
and he intended to run this command every tick (i.e. 20 times a second), so the minecart is expected to run at a speed of 20 m/s.

2. For some low-end computers, such scenario may easily cause chunk loader to work incorrectly, and it could also freeze the map and prevent the player from getting off the minecart. If the minecart were teleported even faster (say 5 block per tick, or 100 m/s), then most computers may have this issue as well.

3. This issue only occurs on version 1.14.x (including 1.14.4), while we didn't find the same scenario on 1.13.2 or earlier versions.