Do you also have problems with the HTML5 player on BBC? I do not understand where exactly Flash Player comes in; I do not get any prompt to install Flash Player on BBC. They appear to use an HTML5 player. Could you share a link for us to test?

what does "reset the browser's profile " mean?

It means to create a clean profile folder: https://forums.opera.com/topic/17177/frequently-asked-questions-opera-for-windows-updated-apr-30-2017/1

As for the website you have linked, it appears the same in the other Chromium browsers I have tried whereas it does not load any content from Chrome which makes it very likely for it to be a problem with the site itself."

I have the same problem- located in Canada - what does "reset the browser's profile " mean? I am not a techie. I just want this to work . Works fine in current version of Chrome - I follow the instructions , on Opera's site no less, to go to Adobe and install - nothing happens. I try to find Flash plugin in Opera to configure -doesn't show up. Like the browser but this is simply a non-starter and I will return to Chrome . I have wasted to much time on this already.

Why would it be a "list issue" on pages without any advertisements?

Because Opera’s ad blocker has broken websites that do not have any ads on them before.

I suggest you first reset your browser’s profile as it will most likely resolve the issue with BBC’s HTML5 player.
You could then proceed and try uBlock Origin instead of the built-in ad blocker to see if it resolves the other problems.

As for the website you have linked, it appears the same in the other Chromium browsers I have tried whereas it does not load any content from Chrome which makes it very likely for it to be a problem with the site itself.

Don't understand the question.

Opera's ad-blocker and Ublock Origin use the same list so if the behavior is the same on Ublock Origin then it's a list issue and should be reported to Easylist.

It wasn't, for me, an issue before the combination of the latest Opera release plus the latest Flash. It only seemed to sometimes effect access to some sites, understandably. In such cases an explanatory text was usually put up by the site. Why would it be a "list issue" on pages without any advertisements?

The latest Opera doesn't seem to have such a detailed user interface to add-ons as older versions.

Don't understand the question.

Opera's ad-blocker and Ublock Origin use the same list so if the behavior is the same on Ublock Origin then it's a list issue and should be reported to Easylist.

AFAIAC the problems I am experiencing have only started since the latest Opera v45.0.2555.812(PGO)

That is interesting. I have been having such issues with the built-in ad blocker from before the recent changes. You may want to submit a bug report in that case.

After another look, I see what you meant regarding the page not being rendered properly. There is a bunch of text outside of the container at the bottom. The content is not even visible in Google Chrome for me though. Is it your website?

BBC uses a HTML5 player which works fine for me as it always has. I have never had to fiddle with the settings to get it to work either. You may wish to consider resetting your browser’s profile.

On earlier versions of Opera, even earlier 45 versions, I did not have these problems - though that was with an earlier and outdated version of Flash.