I had the same problem and stumbled by accident on an odd way how to save the PDF file.
After the PDF file is visible, press the key escape “esc”. A new toolbar above the PDF file will appear. Press the “disc” icon next to the “printer” icon. A window drops down, and now you can save the PDF file in your download folder.
Thx so much, you just saved me!! Have had this problem recurrently since the latest update. Finally have a solution that works.