Nevermind,
I will go for the simple solution instead:
Under Page/Edit ‘Set featured image’. In my case this will work and it is also the simplest solution.
I have exactly the same problem. For the main site everything works as intended.
I tried putting copies of my header images at the place corresponding to arqrichardluis /sp/wp-content/image-header folder but it didn’t solve the problem.
A solution for this would be greatly appreciated!
