Ok heres the info:
Project: Full Length Film
Working with Red One, and RedMX footage
Working off of 2 Huge Lacie HDs - 1st to hold the project files and 2nd with all of the raw footage.
I have edited the scenes in individual Scene Projects. (i.e. Scene 1.prproj, Scene 2.prproj) etc.
I Then made a New Project for the FULLFILM.prproj
Then began to import the scene projects (Entire Project) into the Full Film project file.
In the scene projects all of the clips link up fine, play perfectly.
When I imported the scenes into the FullFilm Project and copied and pasted the footage from the individual scene sequences onto the main FULLFILM sequence. There were a couple of problems.
1. A Bunch of clips say they are offline with the red "Media offline" thing. Then when I go the file and try to relink it, I get the error "Unsupported File format or damaged file". However when i click on the clip and say replace clip and i replace it with the same exact clip it works fine. So the clip is not actually damaged. I can't do this for thousands of files.
2. A weirder problem is some of the clips have these diagonal grey lines, and if you scroll over the clips they are just black. Nothing. So i went and tried to relink the clip again got an unsupported file format or damaged file error, so I replaced the clip with the smae clip that isnt actually damaged it then plays fine in the source monitor but it doesnt link up the diagonal grey line area of the clip.
This is weird. Especially because these clips play fine in Redcine, there is nothing actually wrong iwth the clips themselves.
Hopefully someone can chime in.
Thanks for your time.
I know that I'm a few months late but this recently happened to me as well and I found it frustrating that there were few resources to solve it (hence the reply for yourself, hopefully you've solved it by now, and others in this predicament).
What I did:
*Make the media, the diagonally hashed media, offline and then reconnect the offline media.
This did the trick for me.