Browsers are phasing out support of all ActiveX & NPAPI plugins in favor of native Web apps. This includes Java, Silverlight, PDF, QuickTime and others...
For security reasons, Firefox, Chrome and MS Edge are blocking Flash Player by default now. To overcome this, you must specifically enable the plugin on trusted sites from your browser's advanced settings.
With each new OS & browser update, (Win 10 Creator is no exception), I find it's getting harder & harder to overcome these default settings. It's all leading up to when Flash Player will officially end-of-life in late 2020.
For what it's worth, I have not been able to view Flash content in Firefox for a very long time. I gave up on it. On those rare occasions when I really need Flash Player, I switch to Chrome. Fortunately, very few websites are still using Flash content anymore.
Yes you are correct with this that only all 3 browsers are enabled but not with Microsoft Edge -- still not recognized.
Not sure why?