I have been having this problem in which some apps (examples would be Business Calendar 2 and Telegram) don't show notification properly. The do appear, but only for a split second and then immidiately disappear, without even making a sound. It's a problem with these apps because the way I use them notifications are pretty important to me.
I've been reading a bit and managed to figure out that it might be either an issue with the android version (which I don't believe it is, since it's the latest version and I haven't heard the same problem from any of my friends), or a specific app that prevents other apps from showing notifications. Is there any known app that does that? Or is there another possible cause for the symptoms?
Any ideas for a fix would be great, thanks