Problems with featured image in imported posts

I have a problem with the featured image in the imported post. Autoblog is importing the posts but no featured image is set. I am importing post from the main site in my multisite install to a subsite in same multisite.
- Autoblog are activated in subsite and main site feed is added.
- Addons Feature Image Import and Image Import are activated on subsite

I have tried many different solutions:
- Increased memory limit to 256mb
- Added plugin "Featured Image in Rss Feed" to get image added to feed
- Tried both with setting " Use media:thumbnail tag of a feed item" and "Find the first image within content of a feed item", nothing works.
- Since the image are added to the feed within the description I thougt it would work if I selected the setting "Find the first image within content of a feed item" but same result.

My theme (child theme of Ultimatum theme) required the image to be set as Featured image in post to be displayed in a correct way. But the image just ends up in post content.

Why is the addon Featured Image import not setting the image as a featured image in post as the name suggest?