Using the X key to take items from inventory does appear to still work. Noting this, I tried resetting my controls to default, which did not change the behavior.
If I spam right and left clicks on the mouse very quickly I can get the inventory action to work. I haven't been able to note a specific sequence of right and left clicks to get this to reliable happen. I just click as fast as I can randomly and after a seemingly random number of clicks the inventory item responds.
I noted this as Major since it's a base game mechanic and it's affecting offline play as well.