It is not fixed as well, but I found out some things. If your parrot/entity was in the nether prior to teleporting, and your parrot/entity disappears after going to the overworld, definitely look in the original world spawnpoint. Had a parrot of mine disappear after coming from the Nether into the Overworld and went on to check the world spawn point and it was there. Unfortunately, we lost a parrot from the overworld into the nether, so if they disappear from Overworld to Nether, I am not sure. I tried looking for about and hour and came to no avail. If someone is able to locate their lost pet, please let me know.
Lutetium
It is not fixed as well, but I found out some things. If your parrot/entity was in the nether prior to teleporting, and your parrot/entity disappears after going to the overworld, definitely look in the original world spawnpoint. Had a parrot of mine disappear after coming from the Nether into the Overworld and went on to check the world spawn point and it was there. Unfortunately, we lost a parrot from the overworld into the nether, so if they disappear from Overworld to Nether, I am not sure. I tried looking for about and hour and came to no avail. If someone is able to locate their lost pet, please let me know.