Nothing I can think of has been changed…but that would be the logical thing to look for. In game sounds work, switch to film viewer and no sounds with no changes between apps.
Is it possible something in the film viewer is corrupted? Is it possible to reinstall just that app? I don't know if I'm not hearing sounds when viewing or if sounds are not being recorded when making them.
System info:
iMac 3.5Ghz Intel iCore 7, 16GB RAM, GeForce GTX 780M, Windows 8