Not possible to connect to A2DP

I've got headset SONY that I cannot set to A2DP profile. I've read many questions about that but nothing seems to work. It connects fine via BT, I'm using blueman and Pulse Audio Volume Controle. But when I try to change profile from off or HSP/HFP to A2DP blueman says Failed to change profile to a2dp_sink. When I do the same in AudioPulse it changes in the UI (option is set) but the setting doesn't change. Running pacmd list-cards in terminal shows:

index: 4
    name: <bluez_card.CC_98_8B_E1_56_B6>
    driver: <module-bluez5-device.c>
    owner module: 28
    properties:
        device.description = "WH-CH700N"
        device.string = "CC:98:8B:E1:56:B6"
        device.api = "bluez"
        device.class = "sound"
        device.bus = "bluetooth"
        device.form_factor = "headset"
        bluez.path = "/org/bluez/hci0/dev_CC_98_8B_E1_56_B6"
        bluez.class = "0x240404"
        bluez.alias = "WH-CH700N"
        device.icon_name = "audio-headset-bluetooth"
        device.intended_roles = "phone"
    profiles:
        headset_head_unit: Headset Head Unit (HSP/HFP) (priority 20, available: unknown)
        a2dp_sink: High Fidelity Playback (A2DP Sink) (priority 10, available: no)
        off: Off (priority 0, available: yes)
    active profile: <off>
    ports:
        headset-output: Headset (priority 0, latency offset 0 usec, available: unknown)
            properties:

        headset-input: Headset (priority 0, latency offset 0 usec, available: unknown)
            properties:

Which seems reasonable: if A2DP is not available then I cannot set it up. But I've managed to set it before but after reconnection, it just stopped working and I cannot do that again.

Could you help me to set that up?

PS. I set in my /etc/bluetooth/main.conf

AutoEnable=true
Disable=Headset
Enable=Source

However I am not sure if that's ok: I need to use my microphone from my headset as well for videoconf, doesn't disable=headset disable it?