Ever thought about just using the Silk browser which is optimized for the Fire OS and allowing install of 3rd party apps. I can’t duplicate your issue so no idea where to start. Also that was an old issue that I thought had been resolved, but if you hit cancel and wait for the AFTVnews home page to load then go to files, in the left menu, you can click there and then delete the APK file from there. You can also install X-plore and delete the APK from in that app.