The Topic does not load in ANY mode - you just see a black screen
You launch a Topic in any mode and although a new window is opened for it, this just displays a black screen, with a tiny blue square in the center at the bottom. If you hover the cursor over this blue square, it turns into a 'Pointer' icon, and clicking on it opens a Glossary entry in a new window (that you can see).
You have some text that has been linked to a Glossary Definition (or possibly just hyperlnked to any other content), but this text is set to either not display in the selected mode, or is set to not display in online output.
This did not seem to be a problem prior to UPK 12, but after publishing in UPK 12, the problem occurs.
Locate the text that is a Glossary Term and rework the Bubble Text so that it is not hidden in any mode / output type.