Up Volume button mutes in app

[dwardu_vella]

Using latest iOS 10.3.1 iPhone 6s
When I try increase the volume, the up volume mutes in the app. I have to increase the volume outside the app.

[dwardu_vella]

I also want to mention, this happens when headphones are plugged in. Not apple headphones with volume control.

[B3AU]

Same issue on my iphone6 and sennheiser IE8's

[cllo]

Mine started glitching out, did a swipe up app close n it's fine now

[Deathtrapz]

Still having the same problems but with Apple EarPods so obviously the issue isn't the headphones but this needs to be fixed

[user-removed]

Same problem. Looking for a fix.

[xxiao]

same

[bmil_]

same problem. only solution i have found it locking my phone and then adjusting the volume from the lock screen with the slider