Hello !
So it’s a blank blueprints based project. I add then Cpp code in the editor and created a Blueprint library based. there is only function I can’ find in native BP.
The hot reload button in the editor, which worked until v4.11.0 seems to be broken because there is no hot reload (deleted function in the Cpp code are still there), and the button disappears just after that.
When I restart the editor, the button is there again but same behavior.
When I compile from VS2015 and then restart the editor, the code is loaded.
I don’t know if it’s more explicit 
Thanks !