Attempt a fix for https://github.com/plexinc/plex-media-player-private/issues/669

external/HIDRemote/HIDRemote.m

@@ -1046,6 +1046,14 @@ static HIDRemote *sHIDRemote = nil;
 				case kHIDUsage_GD_SystemMenuDown:
 					buttonCode = kHIDRemoteButtonCodeDown;
 				break;
+
+				case kHIDUsage_Csmr_VolumeIncrement:
+					buttonCode = kHIDRemoteButtonCodeUp;
+				break;
+
+				case kHIDUsage_Csmr_VolumeDecrement:
+					buttonCode = kHIDRemoteButtonCodeDown;
+				break;
 			}
 		break;