It does not matter if Amazon is selling one variation, but not the other. What is important is to look at the history of the specific variation you want to sell.
Has Amazon been on that one in the past? Is Amazon just recently on the new listing, or have they been on often?
You would want to look for signs that Amazon may be hopping on the listing or that they have been on in the past. You would treat it as if it were a separate listing.
What is Amazon is selling one product variation but not the rest?
