Chris, an AdWords advertiser reported the bug last week saying it simply stopped working. He said while in-search ads stopped working, the in-display started working suddenly. Here is how he described the issue:
Before, In-Search was working fine - I got nearly 2.000.000 ad impressions with 50.000 views in just THREE days - it was very easy to get views on your video. In-Display was NOT working at that time. Now, In-Display has been fixed, but In-Search continues not to work properly.
Google's Zee confirmed the issue in the thread saying:
I've checked with our technical specialists, and they confirmed that this issue is affecting some in-search campaigns not to spend their entire budget. The engineers are working hard on fixing this issue as fast as they can. When I get any update on the fix, I'll announce it.
In the thread there are screen shots showing the impression and click issues caused by this bug.
Forum discussion at Google AdWords Help.