Photon Voice native exception

Hi, Our app uses Photon Voice v2.16.1 (Photon mic type). In it's Unity dashboard we ran into an exception : Native Crash - Unknown Function. Stacktrace does not reveal much other than pointing to libunity.so but the logs had the following:

[VoiceScripts.Recorder] [PV] UnityAndroidAudioInAEC: UnityEngine.AndroidJavaException: java.lang.UnsupportedOperationException: Cannot create AudioRecord at UnityEngine.AndroidJNISafe.CheckException () [0x00000] in <00000000000000000000000000000000>:0 


[VoiceScripts.Recorder] Photon microphone input source creation failure: UnityEngine.AndroidJavaException: java.lang.UnsupportedOperationException: Cannot create AudioRecord at UnityEngine.AndroidJNISafe.CheckException () [0x00000] in <00000000000000000

[VoiceScripts.Recorder] Local input source setup and voice stream creation failed. No recording or transmission will be happening. See previous error log messages for more details.

FYI, Our app asks the audio permission just before the voice chat feature is used. The affected device runs on Android OS 6.0. Any help on this would be appreciated