UPDATE - The 336 is now intermittently showing blank too!

Yes, I have seen this recently as well. Even when refreshing the page, the ad spots remain blank. Using FireBug to investigate the blank space, I see that a number of nested ins tags and iframes along with scripts are added, yet ultimately no ad displays. The inner-most iframe contains only an empty document. Other ad spots on the same page will load properly.

I should say, I see this in Firefox. When I open the same URL in Chrome, all ad spots are displaying.

If this is happening to a lot of users, it would explain why I'm seeing a big drop in earnings in recent days.

Hi FD, this is exactly the issue I'm having when inspecting the blank slots. This is happening to me in Chrome although I don't seem to be able to replicate the issue in incognito mode.

I've sent the details to support, they've came back with the standard 'clear cache, check javascript is turned on' etc.

Meanwhile on further investigation, the issue appears to be that while the google adsense script googleads.g.doubleclick.net/pagead/ads is sent over https the advert that is being served is via a http url and this is causing a conflict and the ad is not rendering.

That's a good catch and would be a shame if Google doesn't care.

I was getting blank spots. I made a blank HTML page, added the Google Analytics code to it, and used the URL for my backup ad in the ad unit config, then let it run for a couple of weeks and sent it in to AdSense to show them. They made some tweak (wouldn't tell me what it was) and it still happens, but not as often. You might try that. I think it was before I flipped to https, but I'd have to go back some to check and I don't have time at the moment.

Seeing intermittent missing ads here as well (HTTPS) but only with desktop browsers.

IMO Google's ad server is having issues, or maybe just a lack of advertisers.

I had this yesterday on one of my pages, I just refresh the page and it came back again.

Intermittent missing ads here as well today (HTTPS). Tested both Chrome and Edge. So clearing cache is a BS answer.

I'm also seeing blank ads from time to time. Under Clicks > Impressions, I'm seeing that the impressions don't match the visitors since the blank ads started appearing.

Still seeing blank ads today (Sunday). I guess it would be wize to create backup ad tags :D. Going to experiment with DFP and go with other advertisers to limit the inventory available for Adsense and see if that helps. Should have done that ages ago. Had it setup that way some time ago.

I also notice blank ads but I've ignored thrm

Is it a cause for concern?

I usually have 100% coverage but the last few days it's been 99.6%. I've seen a few blank ad spots. I chalk it up to time of year since I'm entering my slow season but who really knows.

Blank ads have been a way of life for me for years - I think it's a local browser thing. I do most of my work/previewing in Chrome and see blank ads regularly. When I test on Firefox, where I have the browser history turned off, all the adblocks display properly 100% of the time. At least this has been my experience.

I have seen it before, but never this much. One thing i noticed is that on our dev domain the units hardly show at all anymore. It has never been a problem. The domain is behind a login so that might be why. But it is different from what i am used to!

I've been escalated to tech support - will keep you posted!

How do figure out coverage percentage?

I have had this for weeks, been driving me mad but I think I have ressolved my issue. I use Drupal and in the text editor profile I use for pasting code I had inadvertently set it to insert <br> on line breaks. On viewing my page source (right click, "view page source" and not inspect element) I noticed that there were indeed breaks and even the odd <p> within the adsense code.

I have adjusted the setting and tested by refreshing the page multiple times and I get ads displayed every time!

Now when you have ads displaying, Adsense reports are not :D

^{Note: The following message was spliced on to this thread by not2easy - 9:40 am on Oct 21, 2016 <small>(atl -4)</small>}
Hi,

I'm aware as well of this issue with the carriage return <br>, in drupal. I think it's also linked with the content type settings (you can set it to equivalate the cr to <br>) or not.

Best

[edited by: not2easy at 1:47 pm (utc) on Oct 21, 2016]
[edit reason] move cleanup [/edit]