As you may already know, Google recently gave AdMob a complete makeover. While the new UI is great it no longer works with the old AdMob API which is why members who migrated to the new AdMob stopped getting new ad reports.
We now support the new AdMob API and highly recommend linking your new AdMob account by going into Account settings → Linked accounts. Linking the new account will should bring in new reports within the hour and will not cause any duplication of old data.
Legacy notice: We’re keeping support for legacy AdMob accounts, so if you don’t have a new AdMob account you don’t need to take any action right now.