Cloudflare Proxy no longer working with external website

I’ve been using an external blog to post to and recently, I noticed that there were issues with my RSS feeds validating in the Settings section of After some time troubleshooting, I found that turning off Cloudflare’s proxy allows the RSS feeds to validate, but I’d rather not need to disable the CF proxy if possible.

I’ve worked with Manton to whitelist the IPs via the Cloudflare firewall but that doesn’t seem to help. I’ve also tried to disable various settings like botfight mode, changing the security level, etc. but nothing fixes it. Only disabling the proxy seems to allow it to work. I can’t even tell what part of Cloudflare is blocking as nothing from MB IPs show up as an Event in Cloudflare’s dashboard.

Hoping someone here has some suggestions on next steps to try.