SPMC video files miniaturized (not full screen) on Nvidia Shield last fw

[ccentanaro]

Hi , I've a Panasonic TV Oled 55hz1000 connected to an nvidia shield with last version of firmware .
I've another TV Oled 48jz1000 connected to an Xiaomi Box S 2nd Gen

On the Xiaomi the last version apk of SPMC 16.7.4 goes OK to full screen . I intend full-screen when I launch a file video like .mkv or .avi
On the Nvidia Shield when I launch SPMC it'os ok but when I launch the same videos it's miniaturized in the high-left corner of the TV and it's not possible to switch at full screen . When I installed the apk a message appear for both the Boxes like "This app is not secure , android version in too new , do you want to continue?" ad I say YES . The APP SPMC Start OK but every video files is shrunk on the high-left corner on the tv . I wonder if the problem is the android version of the nvidia shield ? or the version of apk file? or some features to change inside settings of SPMC? Thank you

Corrado