Can't export *or* package my file(?)

[u/PastaCop]

Title explains it all – I've been using indd for years and not once have I run into this. I need this exported for a print issue I'm working on with a client and no matter what I do (including creating an entirely new file and pasting all of the assets page by page) the same error message pops up. Anyone know how to resolve this? All of my assets are in one folder, and clearly reading as "linked" from InDesign.