OneSignal push notifications with custom sound

Hi everybody,

I'm using OneSignal for push notifications in Xamarin. everything works fine both at client side and onesignal REST API.

But i'm stuck at a point and cant find a solution. i cannot set a custom sound (a wav file) for notification.

I put the wav file into Assets folder in Project.Android, file is full lowercase (as described), set up the notification channel properties (as described). But noway, i still hear the default notification sound on the device. Im not sure but i think i put the wav files in wrong place. (thats not described in onesignal documentation)

Is there anyone who succeded at onesignal push notifications with custom sounds in Xamarin.Forms for android?

Regards.