Valid RSS Feed

Hi. I’m trying to add our HubSpot RSS Feed URL, but it is coming back with the “This RSS feed URL appears to be invalid” error message. Our website is https://pureintegration.com/, while the RSS feed is a HubSpot blog URL at https://blog.pureintegration.com/rss.xml

We’ve confirmed that another feed URL is working correctly – https://www.wpmayor.com/feed/

We’ve also used the W3C Feed Validation Service to confirm that our blog URL is a valid RSS feed: https://validator.w3.org/feed/check.cgi?url=https://blog.pureintegration.com/rss.xml

Since we’ve confirmed the plugin is working correctly and the feed URL is valid, I’m wondering if the issue is the fact that our RSS feed domain is the same as our website domain. Should we be able to use https://blog.pureintegration.com/rss.xml as the RSS feed if our WordPress website is at https://pureintegration.com/ or does the RSS feed have to be located on a different domain?

Thank you in advance for your help.