Okay, shooting the video in MOV works (simply renaming the MP4 file to MOV did not). It also worked after I remuxed it using ffmpeg. However, even though all of these videos play flawlessly with the built-in Windows 10 video app, they bring my machine to its knees in Vegas Pro 14. Its worse than a slide show and all CPU cores max out at 100%. My machine has an Intel Core i7-3960X 3.30 GHz (6 cores/12 logical processors) with 64 GB of RAM and the disk subsystem is a 4-drive RAID 0 array of Samsung SSDs. For most things it rocks the house!

Bottom line is that even though I have a solution, I don't think I'll be using H.265 unless I find some way to edit them without going through too many hoops. I do very much appreciate everyone's input and suggestions. Thank you all.