I investigated the potential problem but I am not able to reproduce any malfunction.
Just to synchronize ... I am using the latest netPI software V1.1.2.0 you can download from the web site's download section.
So what have I done? I started the container hilschernetpi/netpi-bluetooth:latest with network = host and privileged mode = on and device = /dev/ttyAMA0 mapped. Then I shutdown the device and repowered it, so that the it comes up from a fresh boot.
When Docker was ready back I watched the embedded log entry in the Docker web GUI. You can get to this log window yourself, if you click the container name in the running container list and then click as next to "!Logs".
There I can see the following
starting ssh ...
starting dbus ...
Starting OpenBSD Secure Shell server: sshdStarting system message bus: dbus.
init
Set Controller UART speed to 921600 bit/s
Flash firmware /etc/firmware/BCM43430A1.hcd
Set Controller UART speed to 921600 bit/s
Device setup complete
This log is the output of a console if you would run the container on a standard Raspberry Pi 3 and very helpful, cause netPI has no console due to the web based handling.
As next there is another click you can do once you clicked on the container name in the container list. It is the option ">_ Console". With this option you can immediately jump into the container and run a web based console.
In this console I did call
bluetoothctl and a
scan on on after the other and the device immediately starts scanning:
root@NTB827EB237AC1:/# bluetoothctl
[NEW] Controller B8:27:EB:890:6B BlueZ 5.47 [default]
[bluetooth]# scan on
[NEW] Device 7B:0F:C7:3A:06:AF 7B-0F-C7-3A-06-AF
[NEW] Device 00:1A:E8:2F:75:38 OpenStage 00:1A:E8:2F:75:38
[NEW] Device 58:3D:19:81:CC:12 58-3D-19-81-CC-12
Agent registered
Discovery started
[CHG] Device C8:F7:33:C6:B0:A0 RSSI: -70
[bluetooth]#
So I am sorry, I am not able to reproduce any problem.