Problem with Krypton and Raspberrypi

Greetings to everyone.
I installed Krypton on raspberry with Raspbian operating system and apparently works well.
After scanning my television series they are correctly inserted into the library but when I try to watch an episode I must force full screen viewing by clicking on the item in the left menu.
This happens to me whether the library is both local and remote (NAS).
On Windows Kodi the procedure is totally automatic.
Any suggestions?

Thank you
Bruno