Some time between the 25th and the 27th of July, my "Select featured image" and "Use as featured image" stopped working.
When I try to add or use as featured image, everything looks ok, until after I save.
Then the featured image disappears from the post.
And if I update one of the earlier posts, it looses its featured image.
The only changes I did, was to update plugins.
I've deactivated, tried to save the post with featured image, and reactivated when it didn't work, for all of my plugins.
The one that made it work when deactivated was Automatic Youtube Video Posts. Do you know why?
I can't find anything in the error logs.