I too am having exact same problem: when updating Amazon orders, app continuously asks for captcha, on entering correctly, it repeatedly asks for another. Process repeats & app is unusable as I cannot get updated deliveries.
It's only since current 5.1 version.
Please can you fix this app so it works properly again developers? It used to work perfectly & I use this app a lot & usually love it & depend upon it to keep track of my orders.