Pretty Opaque

Thank you, that works great! I think I didn't understand clearly the difference, or why DEL would remove the whole layer. Now I know to rasterize first, thanks for the quick reply!

Using Affinity Photo 2.0.4 on Macbook (11.7.2). I have made a selection using the Flood Select tool, and see the selection active. I want to delete that area, so I press the delete key (Macbook), but the result is that it deletes the current layer instead of the selection. I also tried the menu: Edit -> Cut, and the result is deleting the current layer rather than the selection. I have used this same sequence on other files and it works as expected: the selected pixels in the current layer are deleted. But other times it does not work. Is there a step I am missing? See screenshot (before pressing DEL).