Debian: Bluetooth-scan not showing any results

I have an Asus VivoMini UN45, and can't get bluetooth to work right. As far as I can tell, the HW is supported and the drivers are loaded (It's the Lite-On adapter shown on Bus 001 Device 002)

$ lsusb
Bus 002 Device 002: ID 0bc2:ab62 Seagate RSS LLC 
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 002: ID 04ca:17ea Lite-On Technology Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

$ hcitool dev
Devices:
    hci0    30:52:CB:05:B9:6A

I can interact with the controller, and start discovery of devices

 $ bluetoothctl 
Agent registered
[bluetooth]# show
Controller 30:52:CB:05:B9:6A (public)
    Name: lux
    Alias: luxie
    Class: 0x00000104
    Powered: yes
    Discoverable: yes
    Pairable: yes
    UUID: Generic Attribute Profile (00001801-0000-1000-8000-00805f9b34fb)
    UUID: A/V Remote Control        (0000110e-0000-1000-8000-00805f9b34fb)
    UUID: PnP Information           (00001200-0000-1000-8000-00805f9b34fb)
    UUID: A/V Remote Control Target (0000110c-0000-1000-8000-00805f9b34fb)
    UUID: Generic Access Profile    (00001800-0000-1000-8000-00805f9b34fb)
    Modalias: usb:v1D6Bp0246d0532
    Discovering: yes
[bluetooth]# scan on
Discovery started
[bluetooth]# 

But nothing more happens. The strange thing is I can see a lot of activity in btmon:

$ sudo btmon 
Bluetooth monitor ver 5.50
= Note: Linux version 5.11.0-10.1-liquorix-amd64 (x86_64)                                                                              0.950933
= Note: Bluetooth subsystem version 2.22                                                                                               0.950939
= New Index: 30:52:CB:05:B9:6A (Primary,USB,hci0)                                                                               [hci0] 0.950941
= Open Index: 30:52:CB:05:B9:6A                                                                                                 [hci0] 0.950941
= Index Info: 30:52:CB:05:B9:6A (Atheros Communications, Inc.)                                                                  [hci0] 0.950942
@ RAW Open: python3 version 2.22                                                                                       {0x0002} [hci0] 0.950944
@ MGMT Open: bluetoothd (privileged) version 1.19                                                                             {0x0001} 0.950945
@ MGMT Open: btmon (privileged) version 1.19                                                                                  {0x0003} 0.950993
> HCI Event: Inquiry Complete (0x01) plen 1                                                                                 #1 [hci0] 10.556060
        Status: Success (0x00)
@ RAW Close: python3                                                                                                  {0x0002} [hci0] 10.556255
@ RAW Open: python3 version 2.22                                                                                             {0x0002} 10.557104
@ RAW Close: python3                                                                                                         {0x0002} 10.557130
@ RAW Open: python3 version 2.22                                                                                      {0x0002} [hci0] 10.557165
< HCI Command: Remote Name Request (0x01|0x0019) plen 10                                                                    #2 [hci0] 10.557219
        Address: 8C:F1:12:A2:6C:BF (OUI 8C-F1-12)
        Page scan repetition mode: R2 (0x02)
        Page scan mode: Mandatory (0x00)
        Clock offset: 0x0000
> HCI Event: Command Status (0x0f) plen 4                                                                                   #3 [hci0] 10.560060
      Remote Name Request (0x01|0x0019) ncmd 1
        Status: Success (0x00)
@ RAW Close: python3                                                                                                  {0x0002} [hci0] 15.555375
@ RAW Open: python3 version 2.22                                                                                             {0x0002} 15.556323
@ RAW Close: python3                                                                                                         {0x0002} 15.556358
@ RAW Open: python3 version 2.22                                                                                      {0x0002} [hci0] 15.556388
< HCI Command: Remote Name Request (0x01|0x0019) plen 10                                                                    #4 [hci0] 15.556466
        Address: E0:63:E5:EF:A9:52 (Sony Mobile Communications Inc)
        Page scan repetition mode: R2 (0x02)
        Page scan mode: Mandatory (0x00)
        Clock offset: 0x0000
> HCI Event: Command Status (0x0f) plen 4                                                                                   #5 [hci0] 15.557261
      Remote Name Request (0x01|0x0019) ncmd 1
        Status: Success (0x00)
> HCI Event: Remote Name Req Complete (0x07) plen 255                                                                       #6 [hci0] 15.574193
        Status: Memory Capacity Exceeded (0x07)
        Address: E0:63:E5:EF:A9:52 (Sony Mobile Communications Inc)
        Name: NoName
@ RAW Close: python3                                                                                                  {0x0002} [hci0] 15.574370
@ RAW Open: python3 version 2.22                                                                                             {0x0002} 15.575566
@ RAW Close: python3                                                                                                         {0x0002} 15.575603
@ RAW Open: python3 version 2.22                                                                                      {0x0002} [hci0] 15.575649
< HCI Command: Remote Name Request (0x01|0x0019) plen 10                                                                    #7 [hci0] 15.575719
        Address: 3C:01:EF:69:26:39 (Sony Mobile Communications Inc)
        Page scan repetition mode: R2 (0x02)
        Page scan mode: Mandatory (0x00)
        Clock offset: 0x0000
> HCI Event: Command Status (0x0f) plen 4                                                                                   #8 [hci0] 15.577235
      Remote Name Request (0x01|0x0019) ncmd 1
        Status: Success (0x00)
> HCI Event: Remote Name Req Complete (0x07) plen 255                                                                       #9 [hci0] 15.594192
        Status: Memory Capacity Exceeded (0x07)
        Address: 3C:01:EF:69:26:39 (Sony Mobile Communications Inc)
        Name: NoName
@ RAW Close: python3                                                                                                  {0x0002} [hci0] 15.594334
@ RAW Open: python3 version 2.22                                                                                             {0x0002} 15.595407
@ RAW Close: python3                                                                                                         {0x0002} 15.595431
@ RAW Open: python3 version 2.22                                                                                      {0x0002} [hci0] 15.595463
< HCI Command: Remote Name Request (0x01|0x0019) plen 10                                                                   #10 [hci0] 15.595524
        Address: E8:31:F3:6C:17:DA (OUI E8-31-F3)
        Page scan repetition mode: R2 (0x02)
        Page scan mode: Mandatory (0x00)
        Clock offset: 0x0000
> HCI Event: Command Status (0x0f) plen 4                                                                                  #11 [hci0] 15.596199
      Remote Name Request (0x01|0x0019) ncmd 1
        Status: Success (0x00)
> HCI Event: Remote Name Req Complete (0x07) plen 255                                                                      #12 [hci0] 15.613228
        Status: Memory Capacity Exceeded (0x07)
        Address: E8:31:F3:6C:17:DA (OUI E8-31-F3)
        Name: NoName
@ RAW Close: python3               

Running all of this as root makes no difference.

Any clues? Btmon gives errors like "Status: Memory Capacity Exceeded (0x07)" and "Status: Page Timeout (0x04)", but my Google-Fu is too weak to proceed.