Missing files during export through AME?

Hi all,

Apologies if this is a repeat, but I have tried searching and can't find anybody with the same issue / not sure of the technical term to search. I am very new to AE and have been working on a project through it. Exported the project quite a few times now and the play back has been fine. However after my last update to it, when exporting some video files are missing and show a colour banding instead. They're not missing in AE and the files have not changed location. So I am not sure what has gone wrong or how to fix it.

Any ideas?

Damian.