How to find offline media in a Productions timeline?

I'm working on a large complex multi-year documentary project using the Productions workflow, so my media is in separate projects than my timeline (original footage is in one project, archival footage in another project, each act of the film is in its own project, and so on, to keep file sizes and autosaves reasonable). When I go to export one of my timelines, I get the warning: "Offline material is present in this export and will be encoded using the Offline Media graphic." I'm not seeing an offline clip anywhere in the timeline, but the timeline is long and complex, so there could possibly be an offline file hiding somewhere. What is the best way to definiteively locate these clips? Because my media is in multiple different projects in Productions, it does not really work to use properties in the Project panel to find offline clips as in Gerik Parmele's method shown here https://www.youtube.com/watch?v=B4KnfCwbuvI Please let me know if you've found or can think of a different way! Thanks!