Bluetooth Headphones not appearing in the Device List

I would like to use new headphones on my computer using Bluetooth. Bluetooth is working, is active. The headphones have been previously charged and set on. On my computer NUC8i3BEH I have Ubuntu 20.0 installed. When trying to activate the headphones on my computer I see other devices in the list but not the headphones (which I placed at 10-20 cm far from the computer). Now, I tried to use the headphones with my IPhone using Bluetooth and it worked. So the problem does not come from the headphones.

I made these tests :

dmesg | grep -i bluetooth; dmesg | grep -i firmware; lsmod | grep bluetooth

Result :

[    5.076272] Bluetooth: Core ver 2.22
[    5.076434] Bluetooth: HCI device and connection manager initialized
[    5.076437] Bluetooth: HCI socket layer initialized
[    5.076458] Bluetooth: L2CAP socket layer initialized
[    5.076482] Bluetooth: SCO socket layer initialized
[    5.216734] Bluetooth: hci0: Firmware revision 0.1 build 26 week 11 2020
[    5.660162] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[    5.660164] Bluetooth: BNEP filters: protocol multicast
[    5.660166] Bluetooth: BNEP socket layer initialized
[   68.679871] Bluetooth: RFCOMM TTY layer initialized
[   68.679879] Bluetooth: RFCOMM socket layer initialized
[   68.679884] Bluetooth: RFCOMM ver 1.11
[    3.750317] iwlwifi 0000:00:14.3: loaded firmware version 46.4d093a30.0 op_mode iwlmvm
[    3.811995] [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)
[    5.216734] Bluetooth: hci0: Firmware revision 0.1 build 26 week 11 2020
bluetooth             552960  41 btrtl,btintel,btbcm,bnep,btusb,rfcomm
ecdh_generic           16384  2 bluetooth

Then:

dpkg -l | grep blue

With the result:

ii  blueman                                       2.1.2-1ubuntu0.3                       amd64        Graphical bluetooth manager
ii  bluez                                         5.53-0ubuntu3.6                        amd64        Bluetooth tools and daemons
ii  bluez-cups                                    5.53-0ubuntu3.6                        amd64        Bluetooth printer driver for CUPS
ii  bluez-obexd                                   5.53-0ubuntu3.6                        amd64        bluez obex daemon
ii  gir1.2-gnomebluetooth-1.0:amd64               3.34.3-0ubuntu1                        amd64        Introspection data for GnomeBluetooth
ii  gnome-bluetooth                               3.34.3-0ubuntu1                        amd64        GNOME Bluetooth tools
ii  libbluetooth3:amd64                           5.53-0ubuntu3.6                        amd64        Library to use the BlueZ Linux Bluetooth stack
ii  libgnome-bluetooth13:amd64                    3.34.3-0ubuntu1                        amd64        GNOME Bluetooth tools - support library
ii  libkf5bluezqt-data                            5.68.0-0ubuntu1                        all          data files for bluez-qt
ii  libkf5bluezqt6:amd64                          5.68.0-0ubuntu1                        amd64        Qt wrapper for bluez
ii  pulseaudio-module-bluetooth                   1:13.99.1-1ubuntu3.13                  amd64        Bluetooth module for PulseAudio sound server
ii  qml-module-org-kde-bluezqt:amd64              5.68.0-0ubuntu1                        amd64        QML wrapper for bluez

And finally:

rfkill list all

With the result:

0: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no
1: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no

Has anyone a clue to solve this problem ?

Is it related to a firewall issue perhaps ?