Rss feed not recognised with domain mapped site

Dear fellow human,

I'm using the domain mapping plugin to get this link: to go to This is working perfectly. The only problem is that when I do this, the rss feeds doesn't work anymore on the new domain. Or to be precise, you can still reach the feed in the browser: But it doesn't validate ( and isn't visible by services like Feedly. So people cannot subscribe...

Any idea why this is and how to solve this?

Tnx, Maarten