> "... but until this week, we failed to see a common thread among these reports."

So Rap Genius, a customer, was able to figure out the issues (from the outside looking in) but Heroku, "on the inside" wasn't able to figure them out?

Or they're playing the "we didn't know, we're going to fix it right away" angle?

EDIT: also, s/failed to/did not/ makes more sense. "failed" implies they tried.