Many thanks to ApliNi on GitHub for pointing out that some people use plugins where Shulker Boxes stack within a slot

This update means that open shulker boxes are given a unique NBT tag that should prevent it from stacking with otherwise "identical" shulker boxes while you are interacting with it.
You can now also only open a "stack" of shulker boxes if only 1 is in the stack.

This has been tested alongside this stacking plugin but others should work -You should still test carefully with your exact server setup!

I can only provide good assurance that the plugin will work without issue if you don't have other plugins that can interfere with shulker boxes/inventory slots