Ebook cover image not working for ebooks

For both .mobi and .epub, when compiling if the cover image is amongst the front matter documents, it is included but NOT as the very first page.
The Kindle .mobi reports an error and no thumbnail is produced.
Doesn’t matter with Add HTML Cover Page is enabled or not for epub.

Andy, I’ve had the same problem: “First Image in Front Matter Folder” doesn’t seem to work properly.

I had the same error on Compiling a MOBI, until I tried the below.

Does it work for you if, before you hit the Compile button, you choose the Cover manually from:
The 5th (of 6) buttons on The Third Column (1st Column being Formats, 2nd being Section Layouts)?
The Drop down for “Cover Image” works for me when I choose the Image manually, instead of relying on “First Image in Front Matter Folder”.

I say works, but in actuality, it is still not showing up as the thumbnail on a Kindle (it works as an Epub)…