Title above and below the thumbnail if longer

What do you mean with splits above and below?
You have titles with take one or two lines, but I don’t see titles which is above and below the thumbnail?
Which browser do you use and is there an browser where it works?

Here is an issue with Safari browser.
Can you add that CSS selectors to your Child-Theme or add the CSS with the Customizer.
We’ll fix it with a next patch version in the code here at the wordpress.org SVN.

.same-category-post-item .same-category-post-thumbnail {
    display: inline-block;
}

.same-category-post-item .post-title {
    display: inline-block;
}