Kishor Kumar

Alright, Mailshark, it might a dfferent issue at your end then. If you’re using a SEO plugin may be setting Open Graph Images individually would help them retrieve the thumbnails easier. Many a times images are not picked as we want them to.

I think the issue with related content where you can’t see thumbnails isn’t really an issue. I was also having the same issue, but realized that it was because browser’s adblock was blocking it.Visit a page with adblock unblocked and the thumbnails should be visible. At least that’s how it was for me.

The blank screen suggests there is a possible PHP error. Are you able to login to the wp-admin? If you can enter wp-admin, try to change the theme to one of the defaults and see if the problem persists. If it does disable all the plugins, and enable them one by one until you discover which plugin was the problem.
Don’t use the culprit plugin again.

With server I meant if multi-site has lower resources usage than two separate installations, since a lot of files would be common esp plugins and themes.

Theme is like clothes, while say domain name is like your head. If you want to look different, you can change clothes and that has nothing to do with the head. Similarly, domain name has nothing to do with domain name as such. Change the theme through wp-admin > Appearance >Themes.