AMAZON UNDERGROUND AND INSTANT VIDEO NOT WORKING ON GALAXY Note 7 via Sprint. Trouble with Amazon Underground and instant video. Security setting were changed to accept unknown sources. Underground app would download and install but it would disappear moments after opening the app. By disappear, the icon and any evidence that I installed it was gone. This happened 5 times before the Underground app stabilized. I then proceeded to install Instant Video. 30 seconds into watching a video, the app disappeared. My Underground app does not give the option to reinstall it only open it but when clicking on open, nothing happens. Took it to Sprint. The store manager tried two other Note 7’s and had the same issue.
Solution: like Krouth above, make sure that you contact the developer of the apps in question. Keep in mind that not all apps are compatible with all Android devices. Given that Note 7 has just been released, there’s a chance that the apps may need to be patched in order to work with your device. Contact Amazon for details.