Podcast artwork won't show or update in Apple Podcasts

Hi, I have launched a podcast through Spotify and then connected it to Apple Podcasts through the RSS feed. I have added the show artwork and a different artwork for the episode and while everything shows correctly in Spotify, the episode artwork won't display in Apple podcasts and is replaced by the show artwork. I have seen that this issue is very common and have tried to change the format to JPEG, under 500KB & with a different name as the image before. But I am not sure what else can be done, does anyone have any advice?