Comment # 4 on bug 1207129 from Christian Almeida de Oliveira

All the behaviour I listed is using BT.
PulseAudio is installed. 
As I see it is time to upgrade to the latest Leap version.

Do you know if there is a way to avoid using "mono"?
Not sure, but checking the PulseAudio cmd pactl list , I came to this part
where the channel Map is set to mono.

Sink #30
    State: RUNNING
    Name: bluez_sink.A0_4A_5E_F5_65_D7.headset_head_unit
    Description: Microsoft Modern Wireless Headset
    Driver: module-bluez5-device.c
    Sample Specification: s16le 1ch 8000Hz
    Channel Map: mono
    Owner Module: 55
    Mute: no
    Volume: mono: 65536 / 100%
            balance 0.00
    Base Volume: 65536 / 100%
    Monitor Source: bluez_sink.A0_4A_5E_F5_65_D7.headset_head_unit.monitor
    Latency: 34116 usec, configured 28000 usec
    Flags: HARDWARE HW_VOLUME_CTRL LATENCY 
    Properties:
        bluetooth.protocol = "headset_head_unit"
        device.intended_roles = "phone"
        device.description = "Microsoft Modern Wireless Headset"
        device.string = "A0:4A:5E:F5:65:D7"
        device.api = "bluez"
        device.class = "sound"
        device.bus = "bluetooth"
        device.form_factor = "headphone"
        bluez.path = "/org/bluez/hci0/dev_A0_4A_5E_F5_65_D7"
        bluez.class = "0x240418"
        bluez.alias = "Microsoft Modern Wireless Headset"
        device.icon_name = "audio-headphones-bluetooth"
    Ports:
        headphone-output: Headphone (priority: 0, available)
    Active Port: headphone-output
    Formats:
        pcm