Cannot install updates with update manager - UI doesn't receive input

unity8 session as a deb

Test Case:
1. With pending updates, open the app drawer, find and launch update-manager
2. Wait until it refreshes the list of packages and try to interact with the UI:
  - Click on details to see the list of updates that will be installed
  - Or click on one of the button 'Remind me later' to dismiss the window or 'Install Now' to install the updates
3. Navigate through the controls with the keyboard

Expected result
The UI is responsive and does what each action is expected to do

Actual Result
It doesn't respond to user input.

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: unity8-desktop-session 1.0.13+17.04.20170221-0ubuntu1
ProcVersionSignature: Ubuntu 4.10.0-11.13-generic 4.10.1
Uname: Linux 4.10.0-11-generic x86_64
ApportVersion: 2.20.4-0ubuntu2
Architecture: amd64
Date: Fri Mar 10 09:12:10 2017
InstallationDate: Installed on 2014-07-23 (960 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: unity8-desktop-session
UpgradeStatus: Upgraded to zesty on 2016-11-15 (114 days ago)