Ah well, this is the thing, it’s all working again now so I’m not sure me sending you the Dorico file will help that much as I replaced the original video with a newly encoded version. however I can if you like. It does use quite a few third party plugins (Kontakt and Engine mainly) and Noteperformer 3 as well though.
The file for the previous cue I was working on (which had similar issues to begin with) does still have the filename for the original video attached although the file itself has since been deleted, I could send that instead.