When an item is dropped into a Dimentional Carver portal and the player gets into the portal back and forth (due to the portals' orientations, sometimes the entities are immediately teleported back after getting out of the portal), the item might disappear.

Minecraft version: 1.18.2
Forge version: 40.1.68
AM version: 1.18.6

My case producing this issue:

1. The respawn point was in the overworld defined by a bed.
2. The player was in the End, opened a Dimentional Carver portal attempting to return to the overworld.
3. An item was dropped into the portal (a shulker box for me), and the player immediately got into the portal.
4. In this case, the player was immediately teleported back to the End after moving to the overworld. (Maybe the item was the same)
5. The item disappeared at both side of the portal and was permanently lost.

• This case appeared only once for me.