This was a tough one and NOT self evident. When I selected Defaults/Floor Structure, the type (lumber) was greyed out and unavailable to check. Hometalk 1 jpeg. I don't know why exactly, but I clicked on the second sizing box (2) under Layer which was set at 7". When I clicked on that box, the Structure Type then became active and changed to I Joist. Hometalk 2 jpeg.
After I changed that to lumber all is good. Thank you for the guidance. Mystery detectives on the job.
Crashmo's post in Unable to frame floor in lumber, only I joists was marked as the answer