Starting with Windows 10 build 1803, if an application captures from a UVC device (I'm using an AverMedia ExtremeCap UVC), then closes, then attempts to capture again the IMFMediaSourceActivate.Activate() method returns E_INVALIDARG. This behavior is reproducible using the MFCaptureD3D example code from the Windows 7 SDK. A workaround for the issue is to unplug and replug the device after the application closes.
I noticed this behavior started happening on two different machines with two different capture devices after the 1803 update.I say "possible" regression since I don't have any way to get a 1709 build to test on to verify this. (Incidentally, if anyone has an easy legal way to install previous builds of Windows 10 for application testing I would appreciate it)
Edit: I found a machine with 1709 still installed, and was able to verify that the issue is not present on that version.