@CShipley I am trying to use the RefreshToken call in your library but get the following exception and error:
NotAuthorizedException - Invalid Refresh Token

After a bit of playing around and reading, it has to do with my userpool setting, I have remember devices turned on (which I want), which means that I get tokens for a device that expires. I think what has to happen is that I'm supposed to send the device information with the StartWithRefreshTokenAuthAsync call somehow. Have you play with this at all? Is there something basic I'm missing here?

My thoughts are that on start up, I'll check if the tokens are about to expires, say in the next 24hrs, and refresh then. Is that a valid workflow?