Add/Subtract From Select Subject No Longer Working

[bruce him]

Working On a Mac using Sonoma in LR Classic, the add or subject feature in masking no longer adds or subtracts from the mask using "Select Subject". The masked area is highlighed in red, but when you go to subtract some of the excess subject, nothing happens using the brush tool. I am using the latest version of LR Classic. 

[richardplondon]

First I would check the Flow and Density settings for your brush - if either's set to a very low value, it can seem as if using the brush is having zero effect. Number keys are one common culprit, for changing these brush settings unknowingly.

Also, you may be used to holding an option key (on Windows it is Alt) when using the brush, in order to Erase. When brushing on a mask set to Subtract, the idea is to actively Paint the areas which are to be removed from the overall mask selection. So you would not want to set the brush to Erase for this purpose. The more you paint, the more removal. Erasing an area of your subtraction mask is the same as leaving it unpainted - either way, it will be doing no removal, 

[bruce him]

The density and flow are not set to low values. I am not holding down an option key when using the brush to subtract from an image. This seems to be a glitch that just started. Thx for your input.

[JohanElzenga]

This sounds like you misunderstand how the option tool works in this case. The option tool allows you to temporarily switch to erase, so you can erase something you just painted in. In other words, it only works if you added brush strokes, but added too much. If you use the subtract brush, then don't hold down the option key because it will do the same (but opposite): it will try to add back something you just subtracted by brushing (it will erase that brushing).

[richardplondon]

if the OP is not holding option down while painting, then there is no misunderstanding there AFAICT.

Other possibilities: if the brush "layer" is set to Invert then one should paint everywhere except for the areas one wishes to remove; or, the mask preview is set to some option that does not make it evident where one is brushing. Or Lr preferences are corrupt / there is a graphic driver glitch maybe.

[JohanElzenga]

Oops, I missed the word 'not'.