RSS Feed does not validate

I have tried to use the Alexa Skills Blueprint for Blog on several different web sites and I keep getting the same error on all of them. It appears to be a problem with the iTunes image line in the Amazon AI for WordPress plugin.

On the first page of the skills blueprint for Blog it asks for the link. When I use the link created with Amazon AI on my WordPress site
I get the following error and can’t go any further:
‘Feed is malformed and cannot be parsed. Please make sure that the feed is a valid RSS format.’

I then used feedvalidator.org to try and trouble shoot. I get this error for this site (and similar errors on all the others i tried)

Sorry

This feed does not validate.

line 28, column 1: href must be a full URL: https://drinktwistedvineswine.com/wp-content/uploads/2019/08/cropped-twisted-logo-sqaure.png [help]

	<itunes:image href="https://drinktwistedvineswine.com/wp-content/uploads/20 ...
"

Looking at the entire feed, line 28 looks different than the other lines which are all populated from the plugin.

Can you advise what the problem might be?

Source: https://drinktwistedvineswine.com/feed/amazon-pollycast/

<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"
xmlns:content="https://purl.org/rss/1.0/modules/content/"
xmlns:wfw="https://wellformedweb.org/CommentAPI/"
xmlns:dc="https://purl.org/dc/elements/1.1/"
xmlns:atom="https://www.w3.org/2005/Atom"
xmlns:sy="https://purl.org/rss/1.0/modules/syndication/"
xmlns:slash="https://purl.org/rss/1.0/modules/slash/"
xmlns:itunes="https://www.itunes.com/dtds/podcast-1.0.dtd"
>
 
<channel>
<title>Twisted Vines Podcast</title>
<atom:link href="https://drinktwistedvineswine.com/feed/amazon-pollycast/" rel="self" type="application/rss+xml" />
<link>https://drinktwistedvineswine.com</link>
<description>A podcast about wine, wine food pairing, recipes using wine, and what's new in the world of wine. Information provided by Z&M Twisted Vines Wines and Winery.  
Think Twisted, Drink Twisted, Be Twisted</description>
<image>
<url>https://drinktwistedvineswine.com/wp-content/uploads/2019/08/cropped-twisted-logo-sqaure.png</url>
<title>Twisted Vines Podcast</title>
<link>https://drinktwistedvineswine.com</link>
</image>
<itunes:owner>
<itunes:name>881 Studios</itunes:name>
<itunes:email>[email protected]</itunes:email>
</itunes:owner>
<itunes:category text="Society & Culture"></itunes:category>
<itunes:explicit>yes</itunes:explicit>
<itunes:image href="https://drinktwistedvineswine.com/wp-content/uploads/2019/08/cropped-twisted-logo-sqaure.png"/>
<itunes:author>881 Studios</itunes:author>
<itunes:summary>A podcast about wine, wine food pairing, recipes using wine, and what's new in the world of wine. Information provided by Z&M Twisted Vines Wines and Winery.  
Think Twisted, Drink Twisted, Be Twisted</itunes:summary>
<itunes:subtitle>A podcast about wine, wine food pairing, recipes using wine, and what's new in the world of wine. Information provided by Z&M Twisted Vines Wines and Winery.  
Think Twisted, Drink Twisted, Be Twisted</itunes:subtitle>
<copyright>Copyright ? 2019 My Blog</copyright>
<lastBuildDate>
Sat, 17 Aug 2019 01:03:52 +0000	</lastBuildDate>
<!--<pubDate>Fri, 18 May 2012 00:00:00 EST</pubDate>-->
<language>en-US</language>
<sy:updatePeriod>
hourly	</sy:updatePeriod>
<sy:updateFrequency>
1	</sy:updateFrequency>
</channel>
</rss>

The page I need help with: [log in to see the link]