I want to report an apparent bug. I am using an M1 chip Mac Mini with Monterey 12.6 OS and Lightroom 12.
Using the masking tool, having selected a Subject and then going to subtract an Object from the section, as soon as the cursor crosses from the menu to the picture window, the Mac automatically opens a new Mac Desktop window, it won't let you remove an object.
It is not a feature I would use often and I was merely trying it as an option but the same does not happen if subtracting the same object using a brush. Easily worked around but no doubt a bug nevertheless.