The latest versions of those themes are for Ghost 2.0.
In general, you should always make sure you are on the latest version of Ghost before using the latest version of a theme, you should not expect every version of a theme to be backwards compatible with old versions of Ghost.
Themes are constantly updated to use the latest and greatest versions of features.
This guide is useful for all self-hosted Ghost users. If you are using Ghost(Pro) then you are automatically upgraded to the latest version of Ghost - Upgrade to Ghost 2.0
I thought i was using version 2 since I am a Ghost(pro) user. Anyhow, I upgraded to Version 2.6.0. But I still have the same problem.
Update
I just noticed that all the of elements with @site helper are not rendered. Not only the logo and cover-image, but the title, url, and description are missing too.