kazam hangs when microphone input is enabled for screencast

[Steve Chadsey]

When I attempt to save a screencast with kazam, and the "Sound from microphone" option is checked, then kazam will hang when I finish the recording.

Steps to reproduce:
1. Open a terminal and run kazam
2. In the GUI, select:
* Screencast
* Any capture area (Fullscreen, All Screens, Window, Area)
* Select "Sound from microphone"
3. Click "Capture"
  a. The Notification area will show a video camera icon with a red "recording" indicator
4. After a second or two, right click on the notification icon and click "Finish recording"

At this point, nothing happens. What should occur is a dialog box asking the user to either edit the recording or save for later. Clicking on the notification icon does not bring up any additional options. 'Ctrl-C' in the terminal does not terminate the application; it needs to be sent a SIGTERM.

My setup:
Dell Latitude 5580
Plantronics Voyager Focus headset with BT600 Bluetooth adatper

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: kazam 1.4.5-2
ProcVersionSignature: Ubuntu 4.15.0-39.42-generic 4.15.18
Uname: Linux 4.15.0-39-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: XFCE
Date: Thu Dec 27 11:45:41 2018
InstallationDate: Installed on 2017-12-12 (379 days ago)
InstallationMedia: Xubuntu 17.10 "Artful Aardvark" - Release amd64 (20171017.1)
PackageArchitecture: all
SourcePackage: kazam
UpgradeStatus: Upgraded to bionic on 2018-10-30 (58 days ago)