Rss feed error and membership plugin

Hi, When I have membership plugin activated and I try to access rss feeds I get this error message:

"This page contains the following errors:

error on line 3 at column 6: XML declaration allowed only at the start of the document
Below is a rendering of the page up to the first error."

When I disable membership plugin the feed works. How do I fix? I am logged in as a super admin.

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