Image glitch in beta6

Hi!
With Preview 6, an image glitch is introduced for me, see the attachment. I have found a workaround, I have to generate optimised media and delete the render cache. The original media is a png File sequence, 1080p25. The glitches happen in the GUI and on the Decklink output.
Cheers,
Jörg
My System is MacOS 10.13.5, 32GB Ram, AMD RX580
With Preview 6, an image glitch is introduced for me, see the attachment. I have found a workaround, I have to generate optimised media and delete the render cache. The original media is a png File sequence, 1080p25. The glitches happen in the GUI and on the Decklink output.
Cheers,
Jörg
My System is MacOS 10.13.5, 32GB Ram, AMD RX580