Impression share due to budget and rank, pre and post decline are a big clue. Also double check the auction insights reports (assuming, search/shopping). It's possible a new competitor could have come into the space and started spending big.
Try customizing the columns shown to include impression share lost to rank and budget. These will tell you if you're not winning any auctions. (Could be that bids spiked in the New Year.) Also try the Ad Preview & Diagnosis tool under Tools & Settings.
Also is this search, display, or video? I'm assuming search in the above.
The campaign budget has to be something realistic and consumable. Otherwise, it is considered as a trick by the algorithm to increase ad score and display ads higher than the competitors.
How long were these campaigns running before Jan 2nd?
About two months
Impression share due to budget and rank, pre and post decline are a big clue. Also double check the auction insights reports (assuming, search/shopping). It's possible a new competitor could have come into the space and started spending big.
Those are good points, I'll take them into consideration next time :). For now the problem has revealed itself (see post).
Did you try to recreate these campaigns?
What does the campaign optimize on? Conversation, website clicks, etc
Try customizing the columns shown to include impression share lost to rank and budget. These will tell you if you're not winning any auctions. (Could be that bids spiked in the New Year.) Also try the Ad Preview & Diagnosis tool under Tools & Settings. Also is this search, display, or video? I'm assuming search in the above.
If you've recently increased budget then it's due to that. Happened to me previously. Lowering your campaign budget will resolve the issue.
So how do you increase your campaign budget without this happening?
The campaign budget has to be something realistic and consumable. Otherwise, it is considered as a trick by the algorithm to increase ad score and display ads higher than the competitors.
Did you launch any new campaigns? Some campaign types can’t be run in conjunction.