I noticed this forever ago but only recently noticed what actually causes it: when playing with a controller, if you open the inventory, once you close it back up, the crafting bar to the left pops back into place with the mouse UI up. It will revert to the controller UI when you hit the left button so it's not a major issue, but a bug nonetheless.
Edit: This doesn't always seem to be an issue. I quit a little while after I made this connection, and then started my world back up, and the issue was gone. But it definitely occurs frequently; I'm just not sure what triggers the condition that causes it to happen.
Steps to Reproduce
On controller: Open the inventory (defaults to a shoulder trigger), and then close it.
On controller: Open the inventory (defaults to a shoulder trigger), and then close it.
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