###Version
Server running: papermc build 86 - 1.16.1

Im encountering an issue where all shulkerboxes isn't stackable with eachother.

Replicate

Create shulkerboxes of default color. Place them around and destroy them. Some shulkerboxes can't then be stacked together.
Seems to be the case for all colors as well.

Expected behavior

The shulkerboxes stack regardles whenever they have been placed or not.

items.yml

allWorlds:
default:
shulker_box: 16
black_shulker_box: 16