After finally fixing the security scan bug in July, MS looks like they've shot themselves in the foot -- again.

I will never, ever again use UT AVI on Windows 10, as my stock intro broke a whole project by refusing to load or be renamed or deleted. I eventually replaced the file temporarily with a random MP4 and got the project open. I then used Import Assist in HOS to convert the UT file to Uncompressed; I think other utilities would be able to do the same thing. M2TS files don't seem to be affected -- this time. There are reports of the update breaking Office.