I’ve been reprocessing some old photos in PhotoLab 4 and having no problems except for one image. It looks fine inside PhotoLab but when I export it I get giant black stripes and a couple of odd artefacts which appear to be related to one of my uses of the Repair tool.
Here’s the photo in PhotoLab showing the Repair tool masks with the offending one selected.
And here’s the exported version. I tried two different JPEG export presets (quite different sized output) and they show the same issue.
I’ve never seen anything like this before.