Hi, True confession time--I habitually do did NOT do clean installs of Capture One Updates or new versions, going back to version 5 when I first gave up LR for Capture One.
But no more. I use a Wacom HD24touch calibrated tablet for my post processing of raw files and after installing Version 8, I started getting big blank black rectangular spaces whenever using the stylus to edit on the tablet. I thought it was the Wacom at first, but then tried PS and LR and I couldn't reproduce the problem. Long story short, I did my FIRST clean install of Version 8.1 and problem solved. Dave Grover and Doug Peterson and other industry people have preached the clean install, but this made me a believer.