HM Newsdesk thumbnail images not showing

I have installed WP 4.3 and like MH newsdesk I new to WP and trying to find my way around.
On the main page the post Thumbnails don’t show I have tried everything i can find on the forums but still the same. I have tried many Themes and it the same with all I have tried except NEWS MAGAZINE which the thumbnails show, but I’m not keen on the theme.
My site> https://isaan-news.services-thai.com/

There seems so many people with the same problem, is it a WP problem or a theme problem?

I contacted MH and they have confirmed that MH newsdesk supports showing images. But did not tell me how because i have the free ver at the moment.
I think I’m the same as most I don’t like to pay until I test the themes if it’s not doing the basics then I worry about spending money.