Custom notification for group

Hello, please help:
Used to be able to set custom notif. per group.
Now, on the Notifications screen ( for the group) with 'Use custom notif." clicked on, after I press Notification tone , I get the screen with the title 'Notification tone" , and a list of ringtones to choose from under a subtitle 'My ringtones' , but the screen goes back after less than a second as if I hit the 'back key'.