(v18, linux)
See attached image.
How to reproduce:
1. Win the battle;
2. On the operation debriefing screen Esc into the menu;
3. Alt+tab out of game and back;
4. Esc from the menu back to operation debriefing screen;
5. Observe a nice interface on the forefront.
One can normally continue by clicking on the Home icon, so it's not a stopper or so.