Thanks borate and National for checking.
I should begin each of my posts with "My video driver is always updated" 😛
DirectX is version 12, which is what Windows 10 should be. I checked the link just in case, but it says there's no direct download for updating, it's handled with the automatic Windows 10 updates.
I'm going to temporarily break a NCH rule and install VP on my laptop and see what happens with that. If it works, I'll use it long enough to stabilize the 8 short videos I need and then uninstall it.
I'm going to say again, I really think there's something going on with VP + Ryzen 7 processors = unexplained headaches.