Hey @Jacquelynne38, so sorry for the trouble! Could you please try again from a private browsing/Incognito window? If it works there, that might indicate that there's something in your cache or cookies that is interfering with ConvertKit on the regular browser window.
You should be able to open a private browsing window by clicking File > New Incognito/Private Window and then navigate to ConvertKit from the window that opens.
If the issue persists, though, please reach out to our team at email@example.com (or via the in-app messenger in your account) with a description of the issue, the name of the broadcast you're trying to upload it to, and attach the image in question directly to your message. One of our Product Specialists will be able to help troubleshoot further!
Thank you! :)