After removing config.ini, the game loaded holding a stack of belts - however after placing that in my inventory, everything appears to be back to normal.
Except empty cursor was bound to A (which is I guess the default?). After changing this, all seems normal again.

So likely just an issue with ...

- Right click does not empty my hand
- Attempting to place a placable object in inventory again causes it to be placed instead - unless there already is an object in that location.

Video: https://www.youtube.com/watch?v=PIdUGwTh9NM

Possibly noteworthy:
- I have an AZERTY keyboard.
- Started since ...