Folks,
Not sure if this is dead thread, but I've run into the same problem. I have always been able to copy pages from one web document and paste into another. Lately I've had issues and pages don't paste. This happens intermittently and only with a few documents.

When pasting, I get the pop-up "Match Color & Styles" and the page looks to be in the Page Gallery, then regardless of whether I chose Match or Don't Match, the page just disappears.
Thanks for any assistance that can be offered. It's an odd issue (suspecting software bug Pro-X.V12.8).