Header vanishing on some pages.

Hi,

I am adding featured image to every post I am publishing. SDome of them works perfect – showing zoomed featured image in the header area.

But in other posts – no chance. You can see only some part of the picture which is quickly sliding up and vanishing.

Examples:
1. good working post:

TeckNet® RAPTOR Gaming Mouse with 2000 DPI 6 Button

2. not working post:

Gold ASP Explorer. Elite Dangerous business model change

3. post with featured picture which does not showing at all:

Homeworld Deserts of Kharak. Rory McGuire – exclusive interview

So where is the problem? All featured pictures are jpg with similar size etc.

Could you please advise why those are behaving different and how to fix it?