Target the layer mask a usr CMD+I Invert. You may have inverted it to begin with by hitting the option key when adding the mask or inverting the selection. If you use quick mask to create the selection make sure you did not change its default settings. I often changed quick mask operation though with the availability of the quick selection tool I do not use quick mask often these days. If I ever start using CC 2018 Select object might be useful in some cases. I often select what I do not want to select then invert the selection I made.
If JJMack's solution doesn't work try this.
After you make the selection, click [Select and Mask] on the context menu at top of screen to open Properties.
In the Properties box click INVERT and then below that check the box for Remember Settings.
Thanks, JJMack. I think I probably did change the Quick Mask defaults (some time ago). I appreciate your quick reply.
Thanks, Joe, for your suggestion as well. I was not aware how to change and remember these settings. Good information! Thanks.