After I did a clean install of Cubase Pro 8.5 on Yosemite, I found that every .cpr file had a blank icon.
I tried various fixes from the Web, but I could only change single .cpr icons.
I finally found this solution which uses Onyx:
Downloaded Oynx direct from the Titanium Software website and installed. Make sure you check ‘Icon services’ in the User tab under Cleaning section, by default it is not checked and I think that is what solves the issue.
Here’s the page with this answer:
https://discussions.apple.com/thread/6606121?start=120&tstart=0
Thanks to iGnome and Guimarca for their posts.
WARNING
Onyx is a great FREE program, but don’t tick other boxes if you’re not sure what they do. I damaged my Mac installation when I did this a few years ago.