I had the exact problem but eventually found the solution. The reappearing cookies are not due to a flaw in CCleaner. The cookies originate from folders installed on your PC, most likely malware. Look in your Windows user folder. Delete odd looking folders. That solved my problem. My malware folders were located in: C\Users\(my user name).
This problem was very frustrating. Google searches of forums provided no solution. Scans by antivirus software did not find malware. Web browser cookies containing "safeframe.googlesyndication" kept reappearing as soon as I deleted them. This happened even when I did not reopen a browser. I considered reinstalling Windows 10 as a solution. In preparation I checked my Windows user folder for files that I wanted to back up. Inside my Windows user folder I found a couple unexpected folders that I did not previously create. I assume the folders were malware installed by some free software I downloaded. I am not sure how how the odd folders installed on my PC. I did not record the name of the folders in order to write this post. But I think the folders had names implying reputable brands such as Oracle. Anyway they were not personal folders. I deleted both folders, including all contents. Then my "safeframe.googlesyndication" cookies problem disappeared. The problem has not reoccurred in the past week. Now when I delete cookies they remain deleted.
