Cannot re-import/re-link iMovie media (not enough space error)

I recently moved from an iMac to a MacMini, and have all my iMovie libraries and media on an external drive. All software is latest version.

When I load any of the libraries, it tells me the media is missing, and to try re-importing. Which I then try, and it says "not enough disk space at selected destination". There is plenty of free space on both my external hard drive and my MacMini.

I have searched for solutions and have tried the "delete/re-install app" approach, which has no effect. If I create a new library and add (the same) media to it, it works fine...however all my previous edits are obviously not there.

I did not Consolidate all Media prior to moving computers, did not realise that was a thing.

Interestingly, if I do try to Consolidate Event Media on one of the libraries or events, I get the error: "There is not enough space on drive "(null)@ to complete the command".

Is there anyone able to suggest I try something else, otherwise I will have lost scores of hours of edits. Simply need to re-link the existing My Media to my actual media. Thank you