I'm having the same problem with Ad Block, but it's more general, allowing popups and ads on almost all sites I visit. It's like Ad Block isn't working much at all anymore. This has been going on more than a month now, longer than my Video Downloader no longer working (which only started after the latest update a few days ago).
I have everything up to date, browser and main Avast, all newest install (verified all yesterday in thread concerning Video Downloader not working).