There is definitevly something wrong with notification sounds resulting even missed calls. After installing today CSSU-Testing 8.2 it rebooted and the first call sounded with my selected ringtone and I thought that everything is OK now. However, later I noticed that I have missed several calls and the following testing demonstrated that no ringtone was played when a call was received. So I rebooted the phone once more and after that the already familiar behaviour returned - the first call ringed with Nokia Tune and the following ones (without changing any settings) with my selected ringtone...