When an entity is in another dimension, teleporting it to yourself while you are also in another dimension different from the entity. The entity will dissappear.
Example: A chicken is in the nether and you the player is in the overworld. Using the teleport command to teleport the chicken to you will cause it to dissappear.
Video Example 1 : Summoned 2 chickens, Chicken far away from the portal will dissapear when teleported.
Video Example 2 : Summoned only 1 chicken.
https://streamable.com/hv7q20
Video Example 3: Summoned only 1 chicken with ticking area.
https://streamable.com/1hpg22
Even though the chicken doesn't teleport the command still registers the entity being teleported to you the player.
[media]This also happens with custom entity with persistent and tick_world with never despawn as true. They would still dissappear upon teleport.
Also, happens when using the teleport method from gametest.
Related issues
Attachments
Comments

Resolving temporarily as Awaiting Response. Is this still an issue in the latest version of the game (1.20.1)?
This ticket will reopen automatically when you reply.

Yes I just tested it and It still happens in 1.20.1

The issue is present in v1.21.3, reproducible in Realms.
Steps to Reproduce:
Create a portal in the nether at [X, 118, Z], and clear out large platforms surrounding it for spawning.
Connect the portal to another in the overworld at [X * 8, 192, Z * 8].
Create an enclosed platform that leads to an additional portal at [X * 8 + 12, 193, Z * 8].
Connect the portal to a nether portal at [X, 249, Z].
Render the nether as a player near the portal mentioned in Step 4.
This is the basic zombified piglin teleporter designed by Ianxofour, see Minecraft Elegance: Instant Gold XP Farm.
This teleporter works when the overworld is loaded by an additional player, but stops working when the player in the overworld leaves the area.