The only thing I can think of at this point is for you to d/l Mojave or Catalina, but don't use it to upgrade your Sierra. Just install it, and without migrating any data or changing it in any way see if Amazon works in the default installation. (You can use your Mavericks partition; just erase it in Disk Utility first. You can erase it only from one of your Sierra volumes.)
It may not work, but it will eliminate a possibility if it doesn't, and if it does, we can run with it from there.
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
