Browser Access to Photos library for Social Networking websites?

Hello, I have Mojave 10.14.6 and whether using Safari or Chrome with LinkedIn, Facebook, or Twitter I cannot get access to my Photos Library to post an image? I navigate from any mentioned website to the Finder sidebar > Media > Photos, then select my Photos library and it does not open? In the dialog box, it says select photos from your list but there are none as the Library does not open?

Things I have tried: I have checked that my library is the System Library. It is (attached photo).

I have checked System Preferences > Security and Privacy > Allow the apps below to access your photos... but only Finder and Viber are seen there and selected - not other apps or browsers are available to select. So therefore no social media sites could access. My Desktop App Viber can access - it does work - but now browser based social media sites cannot??

I also thought perhaps it's an iOS issue, and enabled access to my entire library on my iPhone X iOS 14.4. via Settings>Facebook>Photos: All Photos. Done the same with LinkedIn.

Is this a known issue? I've done some googling, and reading - hence trying all above. Is this feature no longer available? Is this a browser limitation? My partner swears only just recently to be able to do this - and now unable to?

Thanks