Image not showing on older posts

Hello,

I have some trouble with images, if I post a new post and I add a image as first in the post the image shows nice on the startpage. Older posts from post 3, 4 and older the image is not showing annymore. I don’t set a image as featured picture I add it in the post self and always it works but now not annymore.

Only thing I have changed is the older posts not displayed the same size (the shows little bit smaller) I have set the older pictures the same size als the new posts. I have tryed to set it back but still the picture not showing up annymore.

My url is: https://www.limburgsevisser.nl (its Dutch site)
Can annyone tell me what is wrong in the code or what I need to do to set the picture again.

Thanks annyway