Have you tried hooking your Maxx up to different TVs? If so, do you have the same problem with each TV. Some TVs have problems with HDMI connections from phones--seems like I see more complaints about Vizio TVs than others.
Also, have you tried a different HDMI cable? It's always possible that the cable is faulty.
Check your TV's settings to see if there's some sort of HDMI Audio Bypass setting--this is sometimes available if you have a home entertainment system, and want the sound to come out the system's speakers, not the TV's.