I’ve never had issues with Amazon Prime that I can recall. But perhaps the issues some see come from (data left behind by) a failed install, and firmware updates usually preserve your apps and data. So perhaps those with issues that installing the latest update doesn’t solve should uninstall theirs first, starting by using the hidden Android menu’s Apps section to clear the application’s data and then uninstalling it from the same interface, followed by running the system optimizer from the Settings Menu.
Then install the latest version of the Android version (not Android TV version) from either Aptoide Store (on your PPX or Download Amazon Prime Video | Aptoide) or APKPure store (installable on your PPX as an app or Download Amazon Prime Video latest 3.0.272.14347 Android APK)