Editing MXF files: huh?

Not sure how I managed to avoid editing with Canon MXF files, but now it's here and I'm a little stumped. Imported a bunch of interview files. Transferred from client's SSD to my RAID; accessed through FXP as referenced rather than managed. Clicked on "import" on a folder on the SSD and FCP figured it out. 

FCP background tasks reports I'm still importing and rendering, but I've already created about a dozen projects of individual interviews to share with others. Here's my problem. When I select one of these short (10-minute) projects to share/export, I receive this prompt from FCP: "This item cannot be shared while it is still referencing media on the camera."

Another interesting symptom: I can play the media in the project, but if I pause over the timeline, the browser goes black.

What am I doing wrong?

Many thanks,

Tom

This is only a guess but it sounds like your media is still inside the original Canon card file structure and that what FCP is referencing too?
Meaning you copied the clients SSD as is?
I work with Canon C300,C70 and C500 files all the time. When I import I either use the FCP import window or drag the files from the card structure into FCP, BUT I always copy the media to a new destination folder on my media drives. Or in other words I set the media destination inside FCP to my media drive so that FCP copies the clips from the card structure file system to my media drives.
Doing this I never experienced your problems.
Could this be your problem?

For Canon MXF formats, you should always use the import window, choose the appropriate folder to import into (it doesn't have to be in the library of course, but choose where you want it to go). Basically, let it be 'managed'. The import process should import and rewrap the mxf files and copy them into your destination, then apply the correct metadata. Even though it's possible to do, you should not just copy over the files from the card and import in-place. With Canon MXF, you may get segmented files for very long shots, say you were rolling on an interview for a long time. The import process will marry those segments together properly, rather than you having do deal with the segmented MXF.