US pilots aren't credited for kills

[MrBlizzard]

Hi, playing battleground Italy, 1.01.68, turn 41, server game
it seems my US pilots aren't credited for their kills
as in this example, 7 enemy fighters downed, no kills attributed to US pilots
got plenty of cases like this

Edit
it seems it happens mainly when they are used to escort bombers

[MrBlizzard]

As I could see following the battle action report, enemy fighters were downed by P38s
It's also stated here
thanks