We have a pretty big AdWords account with a decent CTR, big budget etc. Recently we noticed that our ads were not being displayed at night. Multiple checks later, we confirmed that the ad visibility issue was not a one time deal. In general, our ads stopped being displayed approximately after 10.00pm. I checked our Google budgets to make sure that there was no restrictive budget there, and there isn't - we're not even close to spending our daily budget. These are some of our top performing keywords in terms of CTR and also conversions. I read through the AdWords Help section about this too but did not find any plausible explanation there. It seemed like our account was going offline after 10.00pm every night! And when I checked during the daytime, our ads were back at their usual #1 positions.
We have a third-party vendor who manages our bids and both they and Google don't have an explanation about what's going on. Does anybody know why this might be happening?