Podcast Artwork Repeated Error during Validation

Hello everyone.

I seem to have a recurring problem.

I've been trying to validate my new podcast in order to submit it to Apple Podcasts, but every time I try to validate it, an error pops up, saying " Podcast artwork must be between 1400 x 1400 and 3000 x 3000 pixels, JPG or PNG, in RGB color space, and hosted on a server that allows HTTP head requests."

I have double and triple-checked my artwork to ensure that it is now a square file, and have uploaded multiple copies of the file, retried my validation, and repeatedly the error keeps coming up.

My most recent artwork files that I've uploaded are 1400x1400 pixels, a dpi of 72, a .jpg file, and with a item size of under 1 MB (it's around 791 KB).

I have tried uploading this multiple times, to no avail.

What should I do?

Here's my URL: https://feed.podbean.com/thegoldstandardpodcast/feed.xml

The name of the podcast is The Gold Standard Podcast

Thanks so much.