Lightbox: With read more link included not all images of the post are shown

I installed the WP Lightbox2 Plugin.
If you see the preview of the post and click on the picture the lightbox opens. But you only can see the first picture and not the other ones which are in the post.
If you open the post and click on the first picture, the other ones are showing without any problem as well.
So the issue is definitely connected with the “read more” or in my case “continue reading” button.

Is there any chance to get all pictures shown in lightbox already on the preview of the post with clicking on the first image?

The site it is about : https://blog.theartpole.com/

Would be really happy for any help or tips.