I am currently trialing Affinity Photo, went to apply a quick mask as described in the tutorial video - but it does not work. Why? Does the trial version have limited functionality? So I open the photo, select Quick Mask from the top icon, a red mask is applied, I select the paint brush tool, set to 100% opacity and flow, click and drag on the photo - but nothing happens. The red overlay is unaffected. I have been through the tutorial several times and I believe I am following it correctly. In the tutorial, the underlying background is revealed through the red overlay under the brush, to create the mask, but this is not working for me. Am I doing something wrong like a missing step or a setting to make? Is the trial version unable to do this? For me this is key functionality i.e. to be able to paint on adjustments, for example as one can in Lightroom (which I am also trialing). If this functionality is disabled in Photo how can i successfully trial it?