QBluetoothServiceDiscoveryAgent: Full discovery always fails

[Ravenboy]

On Macos Sequoia 156.01 on a M# MacBook pro:

after registering the service (which is successful, I start a service discovery scan with DiscoveryMode.FullDiscovery

nothing is discovered, and after about ten seconds I get the following output:

qt.bluetooth.darwin: Manually interrupting IOBluetoothDeviceInquiry
qt.bluetooth.darwin: inquiry failed with IOKit code: -536870186

and my discoveryErrorOccurred() function is called with

<Error.UnknownError: 100>

other times it fails with
qt.bluetooth.darwin: Manually interrupting IOBluetoothDeviceInquiry
qt.bluetooth.darwin: failed to open connection or start an SDP query
qt.bluetooth.darwin: inquiry failed with IOKit code: 10
(and the dscoverErrorOccured function is NOT called.

discovery with DiscoveryMode.MinimalDiscovery does successfully find what is already in the system bluetooth cache

looked here and online, didn't find anything useful