I have the same problem here. The thumbnails do not display at all.
In fact, the “Select Thumbnail” option seems broken. The field seems smaller than it should be and when I click on the arrow to see what options it gives, there is nothing to choose from.
I have the same problem here. Thumbnails do not appear as stated, whether they are set as a “featured image” or not.
It would be great if someone could work this out.
