Layer mask won't work

[Jonathan5E2E]

Hello,

    I made a white solid fill layer and am trying to mask it with the polygonal lasso tool. I make the selection, press delete, but nothing happends unless I invert it, which masks it. It use to just mask as soon as I deleted the selection. What is happening?

[JJMack]

Delete is the clear key an would fill the selection with the background swatch color use d the x to make the background  black

[edgrimley]

Black conceals, white reveals.

[Trevor.Dennis]

I have always used Alt backspace to fill selections whether they be in layer masks or normal layers.