Option key (Mac) not working

The latest versions of PS (I'm currently on 22.5.0, Mac Mini M1, Big Sur 11.5.2) do not seem to recognise the Option Key.  It does not subtract from selections (e.g. using the Quick Selection or Lasso tools) while holding the Option Key down, and clicking on a mask while holding down the Option Key does not show the mask.  I have reset all tools, as well as resetting my Preferences.  I am using a wired Apple keyboard, whose Option Key used to work on pre-Silicon PS versions.

Any suggestions?

Thanks