I love the new updates but seeing as this is a huge part of my workflow I had to reinstall CC 2017. I've tried changing the size/hardness on a couple of Computers with the same result. I am running PS on a Windows 10 PC with all updates installed and the latest Wacom drivers. I have the back button mapped to my pens Rt-Click. When I launch PS CC 2017 it works just fine. I tried to get it to work and I am able to get it to blink on every now and then if I continuously try but I am never able to change size or hardness. Any help would be greatly appreciated.
Initially, this issue was identified as a bug and after the update of Photoshop 19.0.1, it got fixed.
Would suggest you to update the Photoshop via creative cloud desktop app.