Cannot change spotlight image

Hello,
I'm trying to change the spotlight image. There are two images uploaded into the post, the first one that was uploaded was automatically grabbed as the spotlight image. After publishing, we decided we wanted to use the second uploaded image.
I set that one as featured in an attempt, but that didn't change the spotlight image.
I tried changing the order of the images by dragging and dropping the second inserted image ahead of the first in the media upload gallery, so that the sort order reads "1" as the image we want to be the spotlight thumbnail, and "2" as the first uploaded image that we do not want as the thumbnail. This didn't work either.

We're not using a caching plugin, and i've tried multiple combinations of saving changes, updating, and setting as featured to no avail.

On another post, we're having the same issue with the exception that we're trying to change the slideshow image, instead of the spotlight image.

Finally, can the slightshow or spotlight images be set exclusively (ie, different images selected for the spotlight than on the slideshow on single post that is tagged as being both a spotlight and a slideshow feature)?

Thanks