I guess I'm experiencing the same issue when using the contour tool. I often need to offset text a little with like 0.03 radius and most of the time I need to redo this operation over and over since sometimes it adds random artifacts on some of the text outlines and sometime it doesn't.
As I said, it doesn't do that all the time is kind of random, sometime it works properly other times (even with the same text font and text) I need instead to delete the outlines, add the same text again, convert to curve and use the contour tool, set the required radius size and see if it adds the artifacts, rinse and repeat until I got it right. In some cases it doesn't really work, and I have to import the outlines into Illustrator and offset them in there and then re-import it in to Affinity or finish the work in Illustrator.
Also I notice if i zoom in, it affect the radius of the offset, is this the expected behaviour?
In illustrator I can apply let's say an offset of 0.03 radius and zoom very close or far out and it doesn't affect the radius size.
