Inconsistent Fill Behavior on Layer Masks When "Lock Image Pixels" is Enabled

Product Version: Photoshop 2025
Platform: macOS

Summary:

When working with a layer mask on a layer that has “Lock Image Pixels” enabled, the keyboard shortcut `Cmd + Delete` (Fill with Background Color) still works as expected — it fills the layer mask with the background color.

However, the shortcut `Option + Delete` (Fill with Foreground Color) does not work under the same conditions — it silently fails to apply the fill, even when the layer mask is selected and editable.

This creates inconsistent and confusing behavior between the two fill commands and contradicts the expectation that mask editing should be independent of the pixel lock on the main layer.

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Steps to Reproduce:

1. Create a new layer.
2. Add a layer mask to it.
3. Lock the layer using “Lock Image Pixels” (first lock icon).
4. Select the layer mask.
5. Set foreground and background colors to black and white.
6. Press `Cmd + Delete` → Mask is filled as expected.
7. Press `Opt + Delete` → Nothing happens.

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Expected Result:

Both `Cmd + Delete` and `Opt + Delete` should work consistently on the layer mask, regardless of whether “Lock Image Pixels” is enabled — since the fill operation is targeting the mask, not the layer’s image data.

Actual Result:

* `Cmd + Delete` works (fills mask)
* `Opt + Delete` silently fails (no fill happens)