Nope, I will get this resolved, because now I have a much better indication of what might be going wrong!
Of course, as long as I am not completely burning through your patience, haha. Apologies again!
Frankly, I still do not know exactly how it happened, but for some reason, something seems to have not been properly recognized during your playthrough.
Do you remember seeing this at some point after Myrddin brought the furniture into the background? He should enter a sort of thinking idle pose where you can click on him.

Did that ever appear for you?