Facebook launched a political ad archive and imposed new disclosure requirements, as a response to Russian election meddling.

It was a good start, but as the Facebook Political Ad Collector project demonstrated, Facebook isn’t as transparent as it could be – and their system had a lot of holes.

In this “half-day-after” story, we explored those problems – after most of the coverage from other news outlets took Facebook at its word.

In particular, we demonstrated that Facebook’s system for detecting political ads had many false positives – i.e. it excluded ads from, for instance, the Washington State Democratic Party – and that it was missing important categories of data.