Bluetooth Low Energy Notifications not working in newer Qt Versions

With gatttool I am able to receive notifications from my BLE device on Linux.

gatttool -b FF:FF:55:03:9F:52 --char-write-req --handle=0x000e --value=0100 --listen

In Qt the corresponding service + characteristic can be found and its UUID is matching with the gatttool output. However there is no QBluetoothUuid::ClientCharacteristicConfiguration descriptor - actually no descriptor at all. So it's not possible to enable notifications.

In order for a characteristic to support such notifications it must have the QLowEnergyCharacteristic::Notify or QLowEnergyCharacteristic::Indicate property and a descriptor of type QBluetoothUuid::ClientCharacteristicConfiguration.

The notify flag is set, but there's no descriptor to write to.

However when I switch from my newer version of Qt (tested with Qt 5.11.3 on Linux and Qt 5.15.2 on windows) to an older Qt 5.7.1 as mentioned in this question on the Qt forums, everything works fine (notifications are received) - even without writing to any descriptor at all.

Review my pseudocode here.