Thanks Ben.
Trying to follow your instructions, at first I drew a rubber band around the entire TabPage element, that resulted in all of items on page 1 being visible on all the other pages, like a different level that overlaid the others. I quickly canceled without saving.
Then, I was not able to rubber band elements on the pages, it only resulted in dragging the entire page item. So I went to each page, tagged the items individually, and made sure I selected YES on visibility. I did this on each tab page. (Then, when done doing manually, I remembered the right click option to select all items on the page ... aargh!)
When done, I checked the Attributes Table, and saw that the element TabButtonsPage2, now had visibility to 1 vs. the 0 I saw earlier. Went into Preview mode, the Page/Tabs are back again.

It appears to be good now, but let me submit a followup question.
You wrote:
Quote:the Visibility (Visible setting in Property Editor) being set to "No".
Where did you see the Visibility was set to NO, on which element in the Property Viewer?
I could only see the TabButtonsPage2 in the Attribute Viewer. I was unable to tag any individual item on the form/page with that name, or anything similar. What/where is the element TabButtonsPage2, and how could I see it in the Property Viewer and/or Property Editor?
Thanks again for the quick solution. That is more important than the explanation right now.