I've tried setting meta tags for a specific page on my site (https://gamearmada.org/star-citizen-polska). As you can see below I set various opengraph tags but despite that facebook doesn't see this. 

When you check with their debugger what is scraped it seems these are totally ignored (see for yourself). Therefore my question is how can I set those for specific pages when needed? Am I doing something wrong or is there a bug?

If you think this issue is better suited to peer-to-peer support section then please move the topic. Thank you!

I see them on your forum index. So it works in general. The problem might be how you target the page. But that is not visible on your screenshot. 

@opentype thank you for answering! The problem isn't with forum index but that specific Pages page I'd like to be able to share on Facebook and in other places. Please tell me what specifically you want to see and I'll post a screen.

I tested on my site and it seems the tags will only work if the page is public. But your page is not available for guests. It just throws a general access error that won’t contain the meta tags. That’s the problem. 

Now it worked (and I feel like an idiot that I didn't check that first :)). Thank you very much!