Blank ad block means that the code is inserted properly, only the ad code doesn't display ads.
This happens when Google for some reason does not serve ads for the website, page or specific ad block - the block remains unfilled.
Ad Inserter can detect, <a href="https://adinserter.pro/documentation/adsense-ads#hiding-blank-adsense-blocks">hide</a> or <a href="https://adinserter.pro/documentation/adsense-ads#replacing-blank-adsense-blocks">replace</a> blank AdSense blocks.
Please check <a href="https://adinserter.pro/documentation/troubleshooting#ads-not-displayed">Ads Not Displayed</a> for more information.