Podcast listening platforms require cover art images to be within super specific guidelines. Without it, they can't publish the podcast.
When the image is uploaded, it must be:
1.) a perfect square
2.) between 1400 x 1400px and 3000 x 3000px
3.) have a file size less than 1MB (500kb is optimal) among a few other requirements.
4.) file is formatted as a .jpg or .png
– Is there an Episode featured image?
– Is the episode a part of a Series Feed, and does that Series have a feed image?
– Is the Default Feed image compatible?
- Are you using a WordPress plugins that automatically compresses and resizes images? If you're sure the image is the correct size, shape, and format, look into image compression resizing plugins on your site and disable or bypass them just for this image. Images that are too small will invalidate your feed.
If none of these are present (and the right size/shape) then the placeholder grey image will show meaning if you have a square, 1400 x 1400px featured image it will show in the player, if not it falls back to the Series image if it is the right size/shape, if not it falls back to the default feed image, and if that’s not the right size/shape it falls back to the placeholder.