IMO, You are making the mistake thinking that the Mask Overlay will be applied to the photo. Not so!
When you apply a mask (Brush, or Gradient) you must then alter the Sliders in the Adjustment panel for the local adjustment tool result you are wanting.
The MASK Overlay, that indicates the area for a local adjustment, can be changed in color (or B&W) but again a Mask does not alter the image.
Regards. My System: Lr-Classic 12.3 Photoshop 24.5, ACR 15.3.1, Lightroom 6.3.1, Lr-iOS 8.0.8, Bridge 13.0.3, Windows-11.