I would suspect a corrupt registry entry or two. These are not always fixed by reinstallation of the application, even with registry cleaning. I suggest going through these motions though because they are easy to do and you might be lucky, but I have often found the process to have been a waste of time. The problem was only fixed by restoring a good backup image plus other stuff that had been added since the last backup.
I had this problem on my vegas 13 and 19 at the same time and I didn't even use vegas 19 since last month. So I think might be a .DLL problem since I tried to re-register the whole .DLL files in /system32 and then everything corrupted.
Thank you for the information, but it would not seem that the avi/wdp problem is common as it looks like the one and only previous mention of this problem on the forum is this very thread from 11.5 years ago many years before Windows 10 was released.
Glad that you found a solution to your recent avi/adp problem though.