On the PS4 I use an optical cable to my headphones, this problem is very recent like since 2.2 or so, I never encountered it before in FFXIV or any other game I have played on the PS4 so not sure what to say about it really. When I start the game everything work and sounds perfect but after an hour or so sounds start disappearing until all I end up left with is footsteps and a few other ambient sounds.