7.1 Wordpress blog transfer - no thumbnails

Site URL: https://fuchsia-piano-3z6z.squarespace.com/config/

Hello,

I recently moved a clients blog from WP to SS 7.1. All the blog posts came in great but there is no thumbnail. Is there a way to force SS to recognize let's say the first image of the post and make it the thumbnail? There are over a hundred posts, so doing it manually is out of the question. Using the Paloma template if that matters.
Any help would be appreciated.

best

rh

Oddly enough if I just open up the blog post and save it, it will give the post a thumbnail, but the thumbnail wont appear on the blog page, it will just appear if I create a collection, see image.

If I don't "edit" the post there is still no thumbnail.

I'm having this same problem with hundreds of blog posts! Have you been able to sort it out further since this post? Thanks!