Jeff, (& Neil)
Your idea worked. I disabled fast rendering and it produced the MP4.
And you have made me think about something I seem to be forgetting: I have a new PC, with a new OS, and a different graphic card than what I have used for the past three years.
Prior, I used fast rendering as a default. The new PC had integrated graphics and fast rendering was grayed out. I upgraded to a discrete graphics card and fast rendering was enabled again. But it will not work in MP4, as we have found. It does work in WMV, and maybe others I have not tried yet.
I am happy I can once again produce MP4.
I wish I could use fast rendering while doing so.
Thanks for your support and the great suggestion.
~Tom~