Peripheral notifications not showing up

Hello,

I have a system that comes with BlueZ 5.43 installed on a single board
computer (SBC). I have downloaded, built and installed various newer
versions of BlueZ but I am having problems getting them working
correctly.

I have a peripheral (very similar to the gatt server example in the
test directory) with one characteristic. My example was working before
upgrading. However after upgrading, when I turn on notification for
the characteristic it is not showing on the phone.

I do see the notification turn up in dbus-monitor but not in btmon.

signal time=1551910979.743011 sender=:1.38 -> destination=(null
destination) serial=339 path=/ukBaz/bluezero/service0001/char0001;
interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.bluez.GattCharacteristic1"
   array [
      dict entry(
         string "Value"
         variant             array of bytes [
               78 14
            ]
      )
   ]
   array [
   ]

I have tried going back to version 5.43 again but now that is not
working either.

The configure I ran was:
./configure --prefix=/usr \
            --mandir=/usr/share/man \
            --sysconfdir=/etc \
            --localstatedir=/var \
            --enable-experimental \
            --enable-maintainer-mode


To get configure to work without error I needed to install the following:
sudo apt install glib2.
sudo apt install libdbus-1-dev libudev-dev libical-dev libreadline-dev

I have tried various variations on this and done a lot of searching
but don't seem to find an answer.
Is anyone else seeing this issue?
Anyone have any suggestions as what I could try?

Thanks in advance,
Barry