I recently posted about an issue that I was experiencing with my inability to change the diameter of brush tools in PS CC 2017 using my WACOM Intous pen tablet while holding the CONTROL+OPTION keys on my Mac keyboard.
WACOM recently updated their drivers. I downloaded and installed the WACOM driver released on 5/18/2017 - MacOSX - Driver 6.3.22-3 (Mac OS X 10.10, 10.11, & 10.12).
This, it appears, was the cause of the problem. At WACOM's suggestion, I download and reinstalled the previous driver, MacOSX - Driver 6.3.21-8 (Mac OS X 10.10, 10.11, & 10.12), and my diameter sizing issue was solved.
I got the feeling that this driver upgrade has caused some other PS issues for users besides the one that I experienced.
Just an FYI.