iPad Mini 4 has no sound in many games and other apps?

I just got a 4th generation iPad mini and I'm noticing that the sound doesn't work in many games and perhaps other apps. Is there some kind of widespread compatibility problem? It doesn't seem to be a hardware problem. For example, Grand Theft Auto III has sound on the title screen but it doesn't have any sound after that. Other totally different games from other developers have the same problem or no sound at all, for example Piano Tiles has no sound. Other apps like YouTube or Vimeo have no trouble with the sound.

It seems unlikely there is anything physically broken but there are many apps with no sound (most of them games). What can I do?