I couldn't play to Hearts of Iron IV, so I decided to contact the game support to explain them my bug and they answered me that the bug came from my 17.7.2 AMD video driver
and that I should use an older version of this driver to resolve my bug.
That's what I did, and this worked.
So I wanted to show you the bug with this version of the driver and the game and I hope you will fix it.
I put screenshots of our conversation with the game support.