On some posts the set featured image is not picked up and missing when sharing on socials, I tried with adding also img on the og override settings but didn't help.
This does smell like a caching issue to me. Could it be that for the posts where you get this behavior you uploaded an image and then replaced/changed it after?
I thought so too, so I also purged the cache for this post but there was no effect. I was told from the person who reported this that this issue happened before on other posts too. I don't know which exactly I just have a link to this post which was sent to me...