SVG images not working as featured images in theme

Hi,
at first thank you very much for your awesome plugin. I was so happy when I found I CAN use SVG images in WordPress.
But unfortunately I encountered a problem when I want to use SVG image as featured image in theme. Specifically I use theme Marketing from Whoa Themes, but I did not find their support or at least some official page (but maybe I am just bad at googling).
You can see it here at my page, fourth big image (Laser game) should be there, but it is not. So in other places I now use PNG, which looks terrible at other devices.
Do you have any idea what to do with it?
Thank you very much for your answer.
Betty

https://www.ads-software.com/plugins/scalable-vector-graphics-svg/