Adding to this... After making my post i started searching the web and came across a post on Adobes forums which someone posted a fix, to me a temp fix as it gets undone once running Ccleaner or a software like it:
A commenter in Opera forum found and suggested a solution(as following) that fixed the above flash player problem for me and some other Opera user, I hope it help you:
"I've been playing with chrome://site-engagement more. Setting a site to 0, pressing enter and refreshing that page does indeed remove the site from the list.
Also, setting a site to 100 (and pressing ENTER to apply it) and refreshing the site's page often allows flash to work without even adding an exception to the list. I say "often" as it doesn't work all the time. Sometimes I have to close out of the tab for the site and open it up again. Other times I have to repeat that stuff a lot of times or refresh the site page a bunch of times. Then it works, again without adding an exception.
So, maybe try going to chrome://site-engagement and setting all the sites to 100 (making sure to press ENTER each time). Then, for sites where that still doesn't help, keep reloading the site for a while just to see if you can get it to work.
If a site isn't in the list, go to the site first and then it'll show up. If it still doesn't though, you'll have to try the exceptions list. Then it should show up in the site-engagement list where you can then set it to 100.
Not a solution. Just something to mess around with. Also, once it works for a page, I'm not sure if it keeps working (after a restart for example) yet. But, it looks like it persists."
In my case, I set each website to 100, pressing Enter, I repeated the above process for a few time because in the first time was not successful,and refreshing website was not enough but also the website should be closed and then be opened(in my case).
I corrected the path removing Chrome (not sure why they stated that) and adding Opera and such enough it worked.. Although this is something I'll need to do each time I run a cleaning software... I hope an admin with Opera can provide us a solid fix..