404 error when setting up pipe

Hi, I’m trying to create my first pipe. I set the source url to http://www.glen-carbon.il.us/support/newsflash.xml and I’d like the destination to be a post. When I enter the source URL, it shows a spinner that doesn’t stop.

According to the network connections, it attempts a POST to http://_________/wp-admin/admin.php?page=pipes.pipe&task=execaddonmethod

The response is a 404 (not found). Because of this, the Source Output list never updates.

https://wordpress.org/plugins/wp-pipes/