Can't reimport from camera/archive

I have a very important project in Final Cut Pro X (v 10.2.1) that I have spent hours and hours editing, only to find that I cannot export it as it is "still referencing media on my camera". Now, this cannot be the case because the original SD card from which I imported my footage is not plugged in to my computer, and I can still see/edit the clips (they have the little grey camera icon in the left hand corner). I have created a camera archive and tried the 'Reimport from camera/archive' option many times but it does not work (nothing happens in background tasks), I have tried reimporting all the footage from scratch, but it is always the same clips that remain problematic and still display the camera icon. I have spent hours looking online for a solution and I've tried every suggestion listed in answers to questions posed by people with similar problems, including re-linking files and switching the original media files, but to no avail.