RSS Feed validity

Hi there,

I have two feeds that I am unable to determine what the problem is with RSS Feed Aggregator that prevents them from being accepted or validated.

When using them as part of the Feedly RSS Reader, they work fine and pull the correct results. But, nowhere else do they function. I have had luck with WPeMatico plug-in with some feeds, but oddly not both though they are virtually the same. Thoughts?

These feeds pull up the right entries in an RSS Reader:

– https://www.georgiansforthearts.org/?feed=job_feed
– https://www.chathamartsandculture.com/?feed=job_feed

But, when validating both of these feeds return:

– https://www.georgiansforthearts.org/?feed=job_feed

This feed does not validate. line 8, column 45: XML parsing error: <unknown>:8:45: not well-formed (invalid token)

– https://www.chathamartsandculture.com/?feed=job_feed

This feed is valid, but interoperability with the widest range of feed readers could be improved by implementing the following recommendations.
line 1, column 38: Use of unknown namespace: https://webfeeds.org/rss/1.0 [help]
<?xml version=”1.0″ encoding=”UTF-8″?><rss version=”2.0″
line 1, column 38: Use of unknown namespace: https://www.chathamartsandculture.com [help]
<?xml version=”1.0″ encoding=”UTF-8″?><rss version=”2.0″
line 37, column 66: Use of unknown namespace: com-wordpress:feed-additions:1 [help]
<webfeeds:analytics id=”UA-101640269-2″ engine=”GoogleAnalytics”/><site xmln …`