Featured Image doesn’t appear when Page is the source

I've created a Post Grid and checked the "use Featured image box" (following your video instructions to the letter). It works perfectly when I select Posts as the source. However, when I select Pages as the source, the featured image no longer appears, though the rest of the content (excerpt/title) for the pages appear perfectly.

I've ensure that a featured image is present and have wracked my brain but cannot figure out why it isn't working.

Advice would be appreciated.

Thanks.