I have uploaded several ebooks (Mobi format, not bought via Amazon) onto my Kindle personal library, and I can read them without a hitch on my Kindle device, but not on the Kindle app for Mac. Is this a restriction placed by Amazon or a configuration problem? Is there a workaround? All I want is to synchronyze all of my ebook reading on Kindle, Mac and Ipad.
You certainly cannot synchronize them with Amazon software, because they allow onto their cloud only their products.
You can do it however with a very nice application, Calibre, which exists for Mac as well as for Linux and Windows.
If you want, you can get around the DRM (Digital Rights management) restrictions by means of a smart app, which you can download here. This will allow you to synchronize all your e-books across different reading platforms, by using your Mac as the synchronizing agent.