I have a problem that when a lot of apps running in the background sometimes when the app receive push notification (local or remote) sometimes the notification arives without sound.
tested on iOS 9 GM
also hapenns on Whatsapp and Viber
scenario: open and background many apps then receive push notification.
about 1/3 receive without sound in this scenario
If finally and after three updates this problem that should be part of the basic tests from developers should do, still remains , it is a little sad. I am glad that Apple releases new capabilities in each new operating system , including to ensure that their latest devices communicate fine each other, but the basic services in phones that are compatible with each new release, have secured their works fine, and these errors still be standing many months , it is unprofessional.