FCPX will not let me export! Other posts don't help!

FCPX will not let me export. One of my footages is not properly imported, and has a small camera icon at its bottom left corner, symbolising that the footage is not imported. It shows "missing files" when the SD card is not connected. I tried everything... I've read all the support guides; reimported, linked the original to another backup... Nothing seems to be working! It is quite frustrating... Can anyone give me ANY advice please? I'm quite handy with Macs and thought that I don't need to read any posts or support pages, but in these 9 years, this is the first and I am asking you for help.

(FCPX version: 10.2.1)

(The issue is, that during the import, I do not recall pulling out the SD Card or somehow cancelling the import..)

Thank you in advance 🙂