Headphone jack on S7 won't work unless 4 conductor jack is used or SoundAbout app is used

[AC Question]

So for some reason the audio doesn't work on my headphone jack unless:

1. The jack being inserted has 4 conductors (3 black rings. One is for a built in mic on the headphones.)

OR

2. When using a jack with 3 conductors (2 black rings. No built in mic capability), I use an app called SoundAbout and change the settings so that my S7 THINKS it is using headphones with a mic.

Does anyone know what is causing this problem? In other threads people have attributed this to dust or lint build up but I have cleaned it and my non-mic headphones DO WORK as long as I change the settings so that the SoundAbout app tells my S7 that a headphome device with a mic is connected.

Thanks!