I’d like to add some further information to this. The bug in 6.1.1 still exists (Windows 10 1903, at least). Having resolved the original issue via Boris Support resetting my license so that I could activate Mocha Pro on my laptop, when I returned home I needed to transfer the license back to my desktop. I found that if I try to use the App Manager to deactivate Mocha Pro 6.1.1 Multi-license, it reports that both AVX and OFX plugins are in use (which they are absolutely not). I reproduced this on both my desktop and laptop, both running Mocha Pro 6.1.1. The only way around this is to uninstall both the AVX and OFX plugins and then use App Manager to deactivate the license.
I do hope that the developers can resolve this because having to uninstall the plugins first is not nearly as useful. Thanks.