Thank you, Bart. After more clicking around, I can now use the mask tools.
Specifically, I turned on the exposure warnings, played with exposure settings and set the HDR settings to recover max highlight detail. When I went back to the adjustment layer, I was able to bring up the paint/erase choices and the brush icon appeared.
I have no idea what happened or how what I did resolved the problem. I have noticed that I have to have several goes to bring up the brush paint/erase choices whether from the local adjustments panel or from the top tools menu. mouse battery level is 48%. So, that should not be a problem?