https://www.vox.com/recode/2020/10/30/21540443/facebook-political-ad-targeting-transparency-nyu-browser-extension

The company says it has mostly fixed the “technical problems” that prevented some Biden and Trump ads from running.

With less than a week until Election Day, Facebook has admitted to a glitch in the system that handles political ads on its platform. “Technical flaws” related to a new transparency effort that restricted new political ads from appearing on Facebook in the week before the election caused an unstated number of old political ads to not appear at all. The Biden and Trump campaigns both say some of their ads were among them.