Feature Images not always imported

Good day

Thank you for a great plugin.

I’m having issues with some of the articles that don’t import the images as well (feature image). When I started using this plugin it worked fine but after about a month or so it suddenly only imported images for some articles.

The articles are being imported from uberflip.

I have two pages that import a feed:
http://owningnewyork.com/blog/real-estate/
http://owningnewyork.com/blog/lifestyle/

Is there anything I need to do/change to make sure that the images are always imported for all articles?

Thank you

https://wordpress.org/plugins/rss-post-importer/