Hop Studios will help you troubleshoot the oddest of errors. Here’s a noteworthy one we were able to find recently, which will, I hope help us avoid similar problems in the future…
After some initial difficulty in replicating the error you reported, I believe I have tracked down a possible cause of the blank space seen in the position of the ad in the right-hand column.
... and so on, and so on, until the browser stops doing that…
Basically, I think you have two ad networks, each calling the other as a fall-back when there are no native ads to serve. This is causing the blank ad spot (and a lot of redundant ad calls on each page load).
I would advise you that you need to make sure that all your ad networks are set to call the SAME last-resort ad service, and not each other.