> This property was then used when logging visible Tweets that it was in fact displayed. It was a relational ID that told the backend systems exactly which Tweet from which advertiser was being displayed.

It was supposed to be storing these IDs. Did nobody think to test that the thing was, in fact, storing IDs? Especially for something that puts hundreds of thousands of dollars on the line? Even if you're actually passing that value off to some 3rd party system somewhere, you can verify that this slice of your problem (the React component that receives a prop) is doing its job properly. Even if that means stubbing it to log locally. Something?