LR Classic 7.3.1 -- brush NOT working, all else very SLOW (again!)

I've downloaded LR Classic on my Dell PS 15 9550 laptop with dedicated Nvidia graphics card, 16 RAM, LOTS of free disc space, fast processor. The adjustment/masking brush does not work. The sliders that normally show up (such as in radial filter, which does work), do not show up and I cannot use it. I was using the 7.3.1 version, then downgraded by two versions, and adjustment brush still does not work. Not only that, whatever else I try to do is VERY SLOW. I have checked/unchecked the GPU processor button, tried installing 7.3.1 again, and it still does not work. I've tried looking thru Adobe forum but couldn't find answer to fix this.  Virus/malware protection is not preventing the program from working.

Suggestions, please on how to get this darn program working!