I've not needed to use WordPerfect for a month or so, and have no doubt installed a number of Ubuntu upgrades in that time. One of them appears to have affected CrossOver - I was using 17.1.0 under 64-bit Ubuntu 16.04.4 LTS, I'd been remiss in upgrading CrossOver :(
Anyway, the problem observed was that after a very few minutes working with WP, the keyboard became inactive. I could switch to another desktop, and the keyboard was still working there, it was only within CXO that it had 'disappeared'. Fortunately the mouse still worked, so I could exit WP and CXO using the mouse, and try again. Nope, no joy, same problem.
I've just downloaded CXO 17.5.0 and will try again, and report back. If 17.5.0 exhibits the same problem, I will try the latest nightly build and see whether that causes the same problem. Watch this space...