Only a couple of elements are showing on in Elementor

Hi there,
There seems to be some weird kind of limitation as far as the enabling of the widgets in Elementor goes. Even though I am activating them in the back-end, some widgets – like for example the pricing table – NEVER shows under the Elementor widgets when trying to edit a page! Other widgets are showing, so could you please clarify the mystery?

There must be some sort of limitation somewhere …

(running latest version of WP 5.0.3)