I threw the gear into a corner next to where to place it (see screenshot below) and was impossible to grab even though I was standing right next to or on it. No crouching or moving back and forth allowed me to pick it up again.
^The corner
^Can’t pick it up when looking directly at it
I did eventually go to the other side and I am able to pick it up from there, but since that is not only not clear and some people may not even know of the ledge with the tome on it there, this should get patched out when possible. Depending on where exactly the cog is, it may also require you to peak through one of the few pixel wide gaps in the planks to pick it up.
^Very small gap to pick it up again from the Tome-side
I am able to reliable repeat this bug which seems to stretch to the entire wall there to the point where I consider it likely that this will happen in regular games.