Well, I'm two years late to the coversation, but Publisher 1.10.1 is exhibiting this weird behavior for me. When I flow text to a new frame, I, too, get 2.9 pt text in the new frame. This is my first project, and I am working with an import from InDesign that is 180 pages long. No matter what flows to the new frame, it drops to 2.9 pt. I usually catch it, but sometimes a line slips through. I also have gotten the flow back issue with 50 pt font.
When I highlight and resize the text to 12 pt, none of the text styles appear to be correct, so I then have to click a different style and click back on the original style to get things corrected.
This certainly seems like a bug to me. Two years after the original post, and it is still happening. What can I do to stop whatever is happening?