My Galaxy S4 has been doing this for quite a while now. It doesn't display the signal bars anywhere, we have the Sprint AirWave in my home, but I still do not get the full bars that my other family will. I have the stock rom. I changed a few colors in the status bar, but that is all I have done to mess with that up there.
When I have no bars, I can make calls and send texts just fine, like I had full bars. It will display if I have 4G, or 3G, but no bars. It is just annoying, because I don't know if I can make calls, or look up the Pacer's score when I'm on the road.
Once again, I am new to the forum's, and I am sorry if I am posting in the wrong place.
I have called Sprint, and they want me to take it in, but I want to do everything that is in my power before I have to step foot in one of those places.
Thanks for any help!