How to correct flaws the AI masks introduces when pasting settings

I've learned the basics of the relatively new AI-assisted masks and very much appreciate them.  However, when I have to add and subtract from the basics like background and subject, I run into distortions when I paste settings onto related photos.  I have no idea where to start to correct them.  

Background: I photograph a series of my wife's ceramic sculptures/vessels, rotating the work about 30 degrees for each photo and then using the resulting 12 photo series as the basis of a simple film clip on our website.  I have been successfully using the new LRC masking by making development adjustments on one photo (the background and the subject) and pasting them into the other 11.  

However, recently, I have been photographing a work with a glossy, but semi-rough golden interior on an off - white pedestal, all on a white backdrop.  Since I want to develop the base of the work separately from the gold in the top of the work, I've tried to make two masks of the work (one for the off-white base and the other for the golden top; the third mask is of the background, which worked perfectly).  See first attached screenshot - the one with notations describing the masks.  

With an addition and subtractions from the mask on the base, I've been able to make it work, but when I paste the masks, they do not all work successfully in subsequent images.  Distortions such as those shown in the second and third attached screenshots result.  

I've tried lots of searches to find solutions, but can't get anywhere.  Any pointers if the right direction would be appreciated.