I am trying to use Hangouts as my default SMS app (It is also currently the only SMS app installed on my device) because I do like it. However I noticed that sometimes I don't get any notification when I recieve a text message, no vibration, nor sound nor notification in the status bar. As a result, I miss quite a lot of texts. Notice that I do recieve those texts, if I check the app they are there, text bold to indicate they are not yet read. I just don't get the notification. Also, most of the time I do get the notifications without a problem. So to be clear, this is about some SMS's, not about all.
As far as I know this happens when I recieve the message very shortly after I put down my phone (my routine: send text, press 'backbutton' once to get in the hangouts overview, and then I press power to shut of the screen and put the phone down.) If I get a message let's say within half a minute of me turning of the screen I won't have a clue I recieved the message until I go look in hangouts to check. This happens often when someone is quick to respond to my own message, but could maybe be happening with other messages I recieve in that time. I don't think this happens to messages I recieve when the screen has been off for a time, but I can't say that with certainty.
I have a HTC One S currently running CM11, but I had this problem on stock ROM too. However never with the HTC stock messaging app.
I have found similar problems here on the forums, but no satifying answers. I hope someone has a solution?