Can't open the cross-reference panel

No doubt, Rick has the correct answer. Adobe quietly (ok, more likely I was not paying attention) added two panels to FrameMaker a while back: the Cross-References panel and the Markers panel, not to be confused with the longstanding Cross-Reference and Marker panels.

The new ones are enabled with View > Panels and the originals are accessed via the Insert menu. I love the functionality of both newer panels because they replace the need to create a generated list of Cross-References and/or Markers but the naming is confusing, at best. I deal with it by arranging them together in my dock.

I included Variables and Condition tags in my screen shot because while these two pairs are more easily identified by their names, I use them in tandem too, so keeping them together makes my life easier. Designing a custom workspace that simplifies your life is so important!!!

~Barb

Do you have any filter applied in that panel? And what's the icon with the plus sign on it doing?

I fixed your post up to include the image with the text - using the "Insert Photos" icon in the web interface makes it easier for forum participants to see what you're talking about.