"Can't update Feed Proxy" message on every feed

[Alastair Craig]

Hi all — After changing website hosts (and losing an old URL in the process), I am currently attempting to direct my old feedburner URL (https://feeds.feedburner.com/thechickenfeed) to my podcast's new location at https://thechickenfeed.website/category/podcasts/feed

Every time I receive the vague error message "Can't update Feed Proxy."

This happens with any feed I have attempt to update over the past week — even if I save with the exact same settings as-is, with no changes at all.

Has anybody else encountered or found a fix for this? Am I missing something incredibly obvious? Thanks for your time!