The problem is, when Elementor Pro is active. My previous information was incorrect – even with older versions of Elementor Pro the problem is the same – It is not possible to open pages (static blocks) in Pro version of Elementor.
But when I deactivate Elementor Pro, I can open/create new blocks with free version of Elementor. Im not sure if it would be possible to open blocks with Element Pro widgets, because I do not have used them.
Sorry for my previous misleading info.