Weird blank space

There used to be an ebay ad here, but now theres this blank space. Adblock was disabled. I tried on another computer without adblock its the same. What happened?

Probably no ad can be shown in that space, currently. that can happen.

but if theres no ad available, then why dosent it clear that space then when an ad is available put the ad there again

Unfortunately ad networks don't work that way anymore.  They used to give options but no longer.