I think I may have found a bug but i am not sure, I have just upgraded to Marshmallow (build 23.5.A.0.575). Now whenever I receive a voice mail, the voice mail icon shows up and a notification message also displays, but when I swipe the notification message away. the icon also goes (even when there are still un-listened voice mails). On Lollipop the icon still stayed when i did the same actions (the icon goes away when i delete or save all of my voice msg on lollipop).
Furthermore once i swipe away the notification and the icon goes, any new voice mail that I get DO NOT give a notification or the icon. Only when i restart the phone they appear. But once I swipe away the notification there goes the icon (as described above)
This is really annoying because i did not realise I had several un-played voice mail until a week later when i restarted my phone and the notification came thru.
Does anyone else have the same issue? I just looking at the phone services permission setting but that didn’t really help.