Pages will not allow me to make text styles

Pages 13.2, Sonoma 14.0 (though this is a copy of an old post from 7/18/2018 by a user using Pages 7.1 in High Sierra, so this issue affects a number of versions).

Basic issue is that after selecting text, "+" signs for both Paragraph Styles and Character Styles is grayed out. So is "Redefine From Selection."

That previous thread had replies from people who didn't seem to resolve the problem and that user gave up. I'm posting this here as I think I found the problem in case anyone runs into it again.

I'm not sure if this is a bug or somehow a feature, but if you are sharing your document and have it turned on, you cannot create new styles or redefine existing ones, and the "+" signs will be grayed out. You need to Stop Sharing and you'll get those controls back again. Then make the changes you want and re-share if you need to. Hope that helps someone.