I'm not going to go into detail on personal matters which rules out 1, 2, 3.
Re 4, I've mentioned this every time I've seen the false attribution. In particular, and I may have the date wrong, Propstore sold the Ambassador model from the original buyer, I believe in 2015. Their original description indicated it was the "C", but I did speak with them and in they changed it to remove that fact. A beautiful model.
There are a few cases when the studio actually had more than one model built, even though you might think that would be unreasonable. Another is the Romulan Warbird, which was sold by Christie's in 2006. If you look at those pictures, the Warbird is colored light grey; if you look at other pictures the look of a Warbird is green. Did they repaint it?? In the real world there are two models, one green, one grey. The green one was publically on display at the EMP Star Trek exhibit (and if we ever get past the virus, will be at the Skirball in LA this year). Its owned by me. The grey one is - somewhere.