Users/[user name]/Library/Preferences/ Adobe Photoshop CC2017 Settings/Brushes/
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Users/[user name]/Library/Preferences/ Adobe Photoshop CC2018 Settings/Brushes/
Thank you and thank heavens for the time machine. I was searching for ABR files earlier ( forgot what the brush extension was for default saves ) Just got back the organized Brushes.PSP file from the previously installed version.
Adobe.. Please don't mess up again like this.
Also .. please bring back the ability to include brushes as part of the export preferences.