Hello there, I have been having some issues with the thumbnails of blog-posts when I try to post them on Facebook.
For example this post http://www.konsfik.com/bubbles/ is a video-format-post. I have, though, set a featured image for it. When I try to post it on Facebook (by copying - pasting the link) I get an option to choose between three other, unrelated thumbnails (from random posts of my website).
This post http://www.konsfik.com/scanuino-evolution-of-a-robotic-species/ on the other hand, appears with the right thumbnail and title, but is missing the excerpt text.
Generally there are such kind of irregular behaviors when I'm trying to post on FB. Is that something that could in some way relate to the theme itself? Is there any other option I should look into?

Well, After I posted this ticket I noticed that there have been more with the same issue. So I took the step of installing WPSSO (as advised in another user\'s similar problem). However, this did not seem to fix my problem.
I also visited facebook\'s Open Graph Object Debugger (https://developers.facebook.com/tools/debug/og/object/) to try and clear the cache, but there I am getting this error: \"Object at URL \'http://www.konsfik.com/\' of type \'article\' is invalid because it specifies multiple \'og:url\' values: http://www.konsfik.com/, http://www.konsfik.com/.\"
Any ideas about what could be wrong?

Today I found absolutely the same issue. Still got no answer. Keep looking in plugins and .htaccess settings. =(

Well.. within the last 24 hours, I did the following:
-I installed the free version of wpsso plugin.
-I messed around with the structure of my website (I made my home page automatically load my latest posts - instead of directing to a static page that includes a blog item)
-I used the facebook debugger (as mentioned in previous message) -> although I am getting some errors there, things have somehow gotten better... After I fetch new scrape information the post appears normal (with icon and description).

I will keep testing this for one or two more days.

By the way: If I use this setting (automatically loading posts in my front-page) how is it possible to set a featured image for my blog? (without the use of any plugin)
because when I try to share my homepage, facebook automatically publishes my latest post...
Should I, perhaps, try a different setup? Where I have an actual page (with a featured image) in which my blog posts appear?

Any advice on any of the above would be really helpful.

Ma-a-a-an...

I don\'t know if it helps you, but there is what I found:

1. My main problem was that I use big images (1024x1024) instead small (200x200). After crop everything works fine.

2. Facebook debugger marks that my admin name are not applicable. I do not know why! Everything was set up correctly through Yoast SEO. I tried to connect / disconnect admin account in Yoast social setting, and finally it starts grabbing normally.

3. Doesn\'t concerns Facebook but other Open Graph suitable social networks, such as Russian vKontakte. My problem was: unacceptable unicode symbols in file name: I used multiplication sign \"×\" instead using ex \"x\" letter. After I had change multiplication signs to letters — everything starts working fine. So pay attention to file names.

Just one more thing...

I completely found the solution for my problem.

Here it is:

1. Connect thumbnail to page / post / etc

2. Fetch information through Open Graph Object Debugger

3. No thumbnail

4. Go back to page / post editor

5. Do nothing, but just press \"Update\" button without any changes

6. Fetch information through Open Graph Object Debugger

7. Everything is beautiful

8. ...

9. PROFIT!

Thanks alot Grigory!
I haven\'t yet tried it, but I will soon.