Can't receive iBeacon advertisements

[cj8scrambler]

I am unable to receive iBeacon advertisements on a Raspberry Pi with kernel 5.10.17+ using the bleak backend. I don't believe this is realted to he BlueZ "Duplicate Advertisements" issue because this seems to be fixed in Linux 5.9+ (after commit 8208f5a9d435e).

With DEBUG logging enabled, I can see that bleak receives the DBUS InterfaceAdd, PropertiesChanged, InterfacesRemoved sequence from the device:

DEBUG:bleak.backends.bluezdbus.scanner:received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesAdded (/): ['/org/bluez/hci0/dev_C8_C4_6E_B0_74_C8', {'org.freedesktop.DBus.Introspectable': {}, 'org.bluez.Device1': {'Address': <dbus_next.signature.Variant ('s', C8:C4:6E:B0:74:C8)>, 'AddressType': <dbus_next.signature.Variant ('s', random)>, 'Alias': <dbus_next.signature.Variant ('s', C8-C4-6E-B0-74-C8)>, 'Paired': <dbus_next.signature.Variant ('b', False)>, 'Trusted': <dbus_next.signature.Variant ('b', False)>, 'Blocked': <dbus_next.signature.Variant ('b', False)>, 'LegacyPairing': <dbus_next.signature.Variant ('b', False)>, 'RSSI': <dbus_next.signature.Variant ('n', -77)>, 'Connected': <dbus_next.signature.Variant ('b', False)>, 'UUIDs': <dbus_next.signature.Variant ('as', [])>, 'Adapter': <dbus_next.signature.Variant ('o', /org/bluez/hci0)>, 'ManufacturerData': <dbus_next.signature.Variant ('a{qv}', {76: <dbus_next.signature.Variant ('ay', b'\x02\x15\xa4\x95\xbbP\xc5\xb1KD\xb5\x12\x13p\xf0-t\xde\x00I\x03\xe8R')>})>, 'ServicesResolved': <dbus_next.signature.Variant ('b', False)>}, 'org.freedesktop.DBus.Properties': {}}]
DEBUG:bleak.backends.bluezdbus.scanner:received D-Bus signal: org.freedesktop.DBus.Properties.PropertiesChanged (/org/bluez/hci0/dev_C8_C4_6E_B0_74_C8): ['org.bluez.Device1', {}, ['RSSI']]
DEBUG:bleak.backends.bluezdbus.scanner:received D-Bus signal: org.freedesktop.DBus.ObjectManager.InterfacesRemoved (/): ['/org/bluez/hci0/dev_C8_C4_6E_B0_74_C8', ['org.freedesktop.DBus.Properties', 'org.freedesktop.DBus.Introspectable', 'org.bluez.Device1']]

However start_scan() never returns this advertisement. It appears that when bleio performs the _scan_for_interval(), the device gets added, changed and removed during the scan interval. Since the InterfacesRemoved event came in during the scan interval, get_discovered_devices() reports no device.

Looking at the bleak backend implmentation, it seems that the only way to guarantee receiving this advertisement would be to register a callback to handle the InterfaceAdd and PropertiesChanged events.