I am going to continue to add to this post as there is more to the story...
As Don suggested, I deleted PX4AirframeFactMetaData.xml. Rover did indeed show up. I went though the configurations, all seemed good to go. However, I was getting no output from the mains, so signal going to the servos and motors. I spent about a day troubleshooting various forum suggestions. Several have mentioned an issue cycling between Audupilot and PX4, which is exactly what I have been doing.
So, I reinstalled Ardupilot Rover. Was able to get signal to my motor and servos, though something weird was going on there like the RC was not mapped correctly though the config was correct. It did, however, verify that the hardware was working correctly. Now back to PX4, reinstalled the latest stable stack. No Rover Airframe option.
Tried on Linux machine, repeated on Windows machine...happened both places.
Seems a firmware issue when cycling between Ardu and PX4.
Any suggestions? Is there any way to completely reformat the Cube?