Yes sir, I figured out how to do it but what you can't do simply is use it for frequency separation. In Freq Sep retouching you need take patches of the high freq, like skin or clothing texture and use that to patch other areas non-destructively. these can be stacked easily in Photoshop by making a selection, copy, paste and drag to cover, set to normal blend mode and clip to the high freq layer. What occurs in Affinity Photo is creating a new mask which only shows my patch. Not useful. I'm getting by just fine using destructive editing to heal and stamp which works really, really well, but I would like this feature to be easier.