Cant render png/Artifacts in 4k

Hi. I want to render out a imgae sequence. But when I choose .png this happens:

another problem is, that i get these artefact when i render out a 4k .jpeg. (the white boxes)
It works fine in 1080p.
any ideas?
kind regards, phil

Hi PipTogo -

Thank you for your report. This is a known issue and has been corrected in 4.8. If this has become a blocker for you, feel free to try a copy of the Preview release or the release of 4.8 which should be coming shortly.

Thank You

Eric Ketchum

Thanks you for your quick response Eric. I’ll check it out as soon i get home. Kind regards, Phil