The new version of PP CC (13.01) introduces pixels into footage in preview files and 'burns' these pixels into the export.
The source clips do not have these pixels when played on QT Player.
A slightly older version of the same project plays the same footage fine on PP CC version 12. There is thus no problem with the footage.
Since the new file is not backwards compatible, I have to either reconstruct all of the recent edits on the version 12 file or maybe wait for a less buggy update?
Using brand new iMac Pro with plenty of space/ram and have tried flushing preview files and using different codecs in sequence settings but nothing helps. Again, the same footage/same edit plays fine on a project saved on version 12 a month ago...