Update 2 and solved: I disabled all plugins since it was too weird, that I wasn’t able to re-size and even review the featured images I already had in my pages. It appeared that the Fluid Responsive Slideshow Plugin was the guilty, I uninstalled it.
Now assigning featured images and re-sizing and cropping works like a charm again. My slideshow isn’t still like I want it but at least this prob has been solved now. 馃檪
