Why is it when I list 2 very similar items, one will allow international shipping and not the other?

[4thdimensioncollectibles]

I received a message from a buyer in Italy that is interested in one of my items. However, even though I did exclude a few international locations such as Russia, it will only allow him to choose United States and does not give him the option to choose Italy.  I didn't exclude Italy in my set up when choosing destinations to exclude. It is a fossil dinosaur foot print, 266851408028, which should not have any restrictions on shipping as it isn't a prohibited item of any sort.  Oddly enough, once I started looking closer, it seems many of the fossils I'm listing show the same issue.  The weird thing is I have some very similar items listed, where one won't allow internation shipping and the other will. Two examples are fossil shells, 266827416365 (this one will only allow US shipping) and 266848242398 (full international shipping available, but you have to look in my sold items to find it) Both were set up exactly the same, both fossils are from the US, both are pyritized but customer support could not tell me why one could be shipped internationally and not the other. Similar issue with some dinosaur teeth I had listed.  I listed 266872292370, originally with the description "Sharply Serrated nearly 3 Inch Carcharodontosaurus saharicus Dinosaur Tooth" and the original listing didn't have international options.  I changed "Sharply" to "Nicely" and then the international shipping options appeared.  I have to wonder what algorithm eBay runs to exclude items where some get the international option and others don't. This first started happening when the switched from the Global Shipping Program to the new international shipping plan they now have.