Regenerated Images – Inline images in posts still using wrong size.

Here’s where I’m at:

I’ve imported posts from Blogger -> WordPress.

The inline images were all too small. So I used Regenerate Thumbnails to resize all images because Blogger was using the Medium Size dimensions for inline images in post content. So I changed the medium size dimensions to what I wanted. Ran Regenerate Thumbnails, everything went through successfully.

But the inline images in the post never changed to the new size. Isn’t this supposed to happen?

How can I get this to happen?

Example: https://ladolcevitablog.coreytenold.com/2014/05/08/design-decoded-blue-white-bedroom/

That inline image is still using the too small version, as you can see, it’s blurry.

How can I automatically update all of these posts that use the older small size?

Thanks!