Since late last month, many Amazon Prime Video subscribers have been wondering what happened to Dolby Atmos and Vision HDR support. The Dolby icons are still present on such Prime Video content as Jack Ryan and Air, but when you click “Play,” no dice. Well, Prime Video users have figured out that change coincides with the arrival of ads on Prime Video–and if you upgrade to the ad-free Prime Video, you get Dolby Vision and Atmos back. German website 4kfilme.de was the first to notice that videos on the ad-supported version of Amazon Prime Video was no longer delivering the Dolby Vision flavor o…