I am seeing an explosion of impressions on one of my remarketing adgroups. Yesterday we finished with roughly 1,300 impressions, which is about right given the remarketing list only holds about 400.
This morning, this adgroup has over 31,000, and has risen by 5,000 every 15 minutes or so. This is not only costing us in clicks, but it's also destroying our CTR.
There have been no changes or settings touched overnight, and I cannot see why this would happen. Anyone have any ideas as to why this is happening?