I have a Voyage and a Paperwhite and the Kindle app on my phone. I'm reading my current book both on the Voyage and my phone with no problems syncing. I haven't used the Paperwhite for a couple of weeks but I've never had any problems syncing with it either.
Actually the Voyage is the one that syncs most easily. Have you tried restarting it?
One thing I do that most people don't is reset my ereaders at least once a year, often twice a year. That helps me avoid a lot of problems.
Barry
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