I found similar problem where the ‘Add SSH Keys’ dialog does not update the ’.ssh/authorizedkeys’ file for root. This must be done manually. However a separate issue is that the DO Console opens a terminal browser window that has a short copy/past buffer (~128bytes). From the terminal window run nano ’.ssh/authorized_keys’ for root, and update the rsa key by repeating copy/paste multiple times until the entire rsa key value is copied