Featured images mishandled except in twenty fourteen

Example:
#1 https://refugeesupport.net/2016/01/24/500-raincoats-for-calais-batch-1/
#2 https://refugeesupport.net/category/fundraising/project-campaigns/
and then use Theme Switcher...
I suppose that BuddyPress Fun & Community themes are not supposed to show featured images, so I do not put it as related ticket. But I have no idea what is wrong, really.
I saw a "mirror" problem reported here: https://premium.wpmudev.org/forums/topic/why-are-the-image-thumbnails-for-featured-image-so-large-shouldnt-they-be-cropped but apparently the solution is to switch to Twenty Fourteen forever, which is not good enough to me :disappointed: