Problem with empty mask layer

[zBernie]

I was following the tutorial below and took a photo, pasted into another photo.  Then I selected "New empty mask layer".  I was then able to pant with a white brush and see the second photo where I brushed.  The problem is, when I switch to black, it doesn't hide the photo like it shows in the video.  Nothing happens when using black.  I tried selecting the mask, the background layer, and the pasted photo layer, and still black does nothing.  Any ideas why this is not working as expected when painting with the black brush?

(269) Quick Compositing (Affinity Photo) - YouTube

[GarryP]

This sort of thing could be due to any number of reasons.
Please upload a full-screen screen-grab which shows us:

• your Layers Panel (with the mask layer you are trying to paint on selected – also expand layer tree as much as possible);
• your Colour Panel;
• your Brushes Panel (if possible);
• the Context Toolbar settings for the selected tool (have the tool selected when you take the screen-grab).

Basically, show us as much of the state of your application as you can at the point where it is not doing what you expect it to do.

P.S. When giving a link to a video, please indicate the time in the video that is relevant to the issue you are having so people can find it easily without having to watch it all.

[zBernie]

17 hours ago, GarryP said:

This sort of thing could be due to any number of reasons.
Please upload a full-screen screen-grab which shows us:

• your Layers Panel (with the mask layer you are trying to paint on selected – also expand layer tree as much as possible);
• your Colour Panel;
• your Brushes Panel (if possible);
• the Context Toolbar settings for the selected tool (have the tool selected when you take the screen-grab).

Basically, show us as much of the state of your application as you can at the point where it is not doing what you expect it to do.

P.S. When giving a link to a video, please indicate the time in the video that is relevant to the issue you are having so people can find it easily without having to watch it all.

Thanks for your suggestions.  I was able to reproduce the problem briefly when using the color wheel selector, and switching between black and white.  Then I switched to the sliders and I could see that each RGB slider were all 0 for black, and 255 for white.  It worked as expected then.   I switched back to the color wheel and it worked as well.
I suspect that I was not at full black when using the color wheel.  But all is well now!