Can't import featured image

Hi !

I have a blog on https://www.work-and-care.fr that i want to be exported with Rss multi importer.
In all the articles i imported, the ones with only a featured image only are not correctly imported : the featured image is not there.
I have to put one in the text to be imported well in the multirss as a featured image (in the new wordpress)

I checked the option Select how to use the image (in excerpt and/or as the Featured Image) : featured image only.

but apparently it doesn’t work.
For instance my last article has only a featured image, can you help me to import it correctly?
regards,

https://www.ads-software.com/plugins/wp-rss-multi-importer/