Rebuilding existing images issue

[Madal]

Not sure what might be the issue here but I can't make the "Rebuild existing images" to take effect. As i understand it should resize all thumbnail images, also the ones that have uploaded with different size before. But all my thumbnails in forums remain same, only new ones uploaded take the effect. I have cleared the cache. 

Any suggestions?

 

[Marc]

I would need some examples of where you believe its not showing correctly. Also, could I confirm you have waited for the background tasks to complete rebuilding?