Brush add/remove after mask selected not working

Hoping for some help.  I am running the 15.5.1 updated version of LRC.  All of a sudden today I am having issues with the brush feature when using masks.  Both when I try to add a mask using a brush, but also when I select (e.g. ‘Subject’) and then try to use the brush to add or remove parts of the mask.  When I try to remove a portion of the mask the brush doesn’t do anything.  Interestingly, when I try to use the brush only, (with the show overlay box checked), it does not highlight the selection in the normal medium red color.  It looks like there is a small hint of red from the brush, but it is barely visible and adjustments don’t seem to really have much effect.  If I hit ‘create new mask’, then ‘select subject’ it highlights in a medium red just like it always has.  The brush feature just doesn’t seem to do anything anymore.  I’ve tested this brush issue with a radial gradient and a linear gradient, and the same issue, the brush does nothing anymore.  I’ve tried restarting.  This may sound naive, but it did occur to me to try and uninstall/reinstall, but I am afraid I will lose all my edit history and I am working through a big batch of vacation photos.  I’ve tried searching to forum and the internet to fins some answers but I can’t seem to find any matches.  Any ideas?