We've seen a number of you reporting that new episodes don't seem to properly push through to iTunes sometimes, or your new artwork doesn't show on iTunes, despite all settings on SoundCloud are correct.
iTunes provides a way to refresh the cache for your RSS feed on their end. Here's how to do that:
Go to http://podcastsconnect.apple.com/ and log in with your Apple ID. Click the artwork for your show and then click the "refresh featured" link. It may take up to 24 hours for your iTunes Store listing to update. Keep in mind that current subscribers will get your latest episode as soon as they refresh their subscriptions, regardless of what's being displayed in the iTunes Store.
Thanks to our good user@shawnmx
, who provided this advice in the first place. We've reported this to our product team for review from our end, too.
Hope this helps!