Minecraft Version: 1.20.1
Mod Version: 1.2.1
Mod Loader: forge

Description:
Dupe glitch, with Sculk Transmitter and Shulker Box
If a Shulker Box is broken while a player is using a Sculk Transmitter access it, the inventory is not closed and items, that now are within the broken shulker, can be removed from the non existent inventory.

To Reproduce:
Steps to reproduce the behavior:

1. Open a Shulker Box with a Sculk Transmitter.
2. Break the Shulker Box
3. Remove any items from the box.
4. Place the dropped Shulker Box
5. You now have duped the item.

confirmed. this happens because the transmitter isn't constantly checking if the block exists or not. it only checks when opening the transmitter.
there are two possible fixes:

• make shulker boxes not supported with transmitters
• find a way to continuously check if the block exists while using the transmitter

is this an issue for fabric?

fixed for forge in d32baa2

Fixed on Fabric