When opening a shulker directly from the inventory using a right-click, the client inventory will desync from the server.
This desync lasts until the client manually updates their inventory using any means, including clicking an empty slot in their inventory. Until then, picking up items from the ground and other similar activities will not update the client side inventory. It's like the client inventory is completely frozen.
The same bug does not appear when opening a shulker from the hotbar, unless you then open another shulkers in your inventory.
When opening a shulker directly from the inventory using a right-click, the client inventory will desync from the server.
This desync lasts until the client manually updates their inventory using any means, including clicking an empty slot in their inventory. Until then, picking up items from the ground and other similar activities will not update the client side inventory. It's like the client inventory is completely frozen.
The same bug does not appear when opening a shulker from the hotbar, unless you then open another shulkers in your inventory.