FPSCaracther blueprint always empty after closing it


I’m following the FPS C++ ( tutorial from the wiki and each time I close the BP_FPSCharacter which is a FPSCaracter blueprint
it cannot be opened again, well it can but it would be empty.

Here i create a new FPSCarachter blueprint, double clic on it

I do my stuff, compile, save, then hit the cross on the tab to close it

Then if I want to re-open it again to change something all I get is this empty window

What am I missing?

Note that my projectile blueprint which was created/modifier/closed the same way can be opened/closed as much as I want