Feature Image in post it's cut, shows ok in thumbnail on the sidebar

Hello I am using the latest version of Chocolat free theme.
I have a problem with the feature image on the post. For some reason the image is incomplete, only part of the image is shown, not the full image. I have tried to resize it, but still no success.
If you go to https://www.lowfodmapdiets.com/chocolate/ you will see what I mean. The same picture shows ok in the thumbnail of the sidebar.
Thanks a lot and compliments on your theme, I really like it.