It sounds like you are selecting layers that are inside of a Switch layers.
Switch layers are a special type of group that only shows one of its layers at the time.
If this is the case and you don't want a switch layer there, you can select all the layers in the switch layer and move them outside.
No, its not a switch layer.
It was always different... it worked.
And now.. :/
If i select the group layer there is only the red square without any points i have made in any layer...
if i select one of them.. so i select the head. only the head layer is visible.
and so on..
Doesn't look like you have any fill/stroke created.
But if you want to see the vector curves, you'll need to enable paths for each layer, in the quick settings.
And probably enable "paths for new layers" in the preferences.