A pdf reader with highlighter/notes functionality that can sync the pdfs AND their hightlights/notes across multiple devices on different platforms. I was very

A pdf reader with highlighter/notes functionality that can sync the pdfs AND their hightlights/notes across multiple devices on different platforms. I was very surprised to find such a thing doesn't exist (to my knowledge). I've tried sending pdfs to my Kindle account and it silently fails (the pdfs never show on my device). I tried using a pdf reader+Dropbox combo, but the pdf reader kept having trouble saving to Dropbox and creating "MyPdf (2).pdf" copies. I would end up with 20-30 copies, making it impossible to tell which one had the notes I was looking for.