Yep. I have one PC where I let the update install and M-PC doesn't output DMX on it. My other PC - my main console PC that I don't connect to the Internet except to pick up security updates when I'm sure they don't cause problems with M-PC - doesn't have the update yet and doesn't have the problem.
Plus there are multiple reports of this issue on the official Martin M-Series Users Facebook group.
For me it is the KB4056892 update, but some on Facebook have mentioned KB4056891 as well. Uninstall those patches and M-PC should work. Unfortunately those are patches for the nasty Spectre and Meltdown security flaws. So hopefully Martin can update M-PC to dealwith the issue pretty quickly. Meanwhile I'm leaving my main console PC disconnected from the Internet.