Update - check the last entries in this thread - there is a workaround and one user actually figured out the potential source of the bug too.
Solusion in short: Change the layout to Bottom - Preview or Bottom Spit (so that only one page a time is in the Pdf-pane). Then the PDF viewer works fine.
(however if you zoom out the pdfpane then the PDF-viewer window will always skip to the page centered in the pane - that is the bug).