Unable to add fields to screens

[tobias]

I'm unable to add fields to any screens in any project. No idea what has happened. 
It's grayed out. I can remove fields, but not add them. 

I can add fields from field configuration by selecting a screen. But not from the screens configuration.

[Nicolas Grossi]

@tobias fields are not add on the screen properly, fields are add on configuration section and you have to select the screen (checkbox) where the field is going to be displayed.

HTH

Nicolas

[tobias]

@Nicolas Grossi 
Thanks, Nicolas. I can add the fields by going to the configuration section using the checkbox for each field and then selecting the different screens. But that is a way slower and more tedious process. 

I want to know why I can't add the fields by going to the screens, like I've done before.