Metadata Management on Android not working?

Hello,

I'm using Calibre to manage and transfer books to my Android Kindle app. I encounter problems when trying to update my library metadata and keep this information synced with my device.

With Automatic Metadata Management switched on, if I update the metadata of a book in my Calibre library--say, by changing the author name and the cover--Calibre should sync this with my device whenever it is connected, right? When browsing my device within Calibre the author name shows the change and the cover shows as unchanged, but on the Kindle app neither the author name or cover have changed.

Another option is to "send to device" once I've made the changes but this creates a duplicate on the device (sometimes Calibre says "2 books" next to the device entry, other times it doesn't, but the Kindle app shows a duplicate every time).

At the moment I think the only way to ensure all information is synced between my Calibre library and Android Kindle app is to delete my android books whenever I've made a change and then send them to the device again.