Several notification icons are no longer showing.

After a recent update to Ubuntu 16.10 Beta 2 (I did not notice exactly when) several notification icons are no longer showing in the notification area. Google Chrome, Slack, WMail and Dropbox are no longer appearing. The applications are running in the background as intended, but there's no icons for them. In Ubuntu 16.04 I have notification icon for all of them. I am running Ubuntu 16.10 Beta 2 fully updated.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: unity 7.5.0+16.10.20160906.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.8.0-19.21-generic 4.8.0-rc8
Uname: Linux 4.8.0-19-generic x86_64
NonfreeKernelModules: wl
.tmp.unity_support_test.0:

ApportVersion: 2.20.3-0ubuntu7
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity:Unity7
Date: Mon Oct 3 20:34:20 2016
DistUpgraded: 2016-09-14 14:22:01,828 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process "./xorg_fix_proprietary.py" (No such file or directory) (8))
DistroCodename: yakkety
DistroVariant: ubuntu
DkmsStatus:
 bcmwl, 6.30.223.248+bdcom, 4.8.0-19-generic, x86_64: installed
 tp_smapi, 0.42, 4.8.0-17-generic, x86_64: installed
 tp_smapi, 0.42, 4.8.0-19-generic, x86_64: installed
GraphicsCard:
 Intel Corporation HD Graphics 5300 [8086:161e] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Lenovo HD Graphics 5300 [17aa:3906]
InstallationDate: Installed on 2016-08-18 (46 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
LightdmDisplayLog:
 [dix] EventToCore: Not implemented yet
 [dix] EventToCore: Not implemented yet
 (II) AIGLX: Suspending AIGLX clients for VT switch
 [dix] couldn't enable device 14
LightdmLog:
 [+63284.04s] DEBUG: Seat seat0 changes active session to
 [+63290.18s] DEBUG: Seat seat0 changes active session to c2
 [+63290.18s] DEBUG: Session c2 is already active
MachineType: LENOVO 80HE
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.8.0-19-generic root=UUID=e90f8ff2-77bb-4ba1-9a79-ea803096989f ro rootflags=subvol=@ quiet splash vt.handoff=7
SourcePackage: unity
UpgradeStatus: Upgraded to yakkety on 2016-09-14 (19 days ago)
dmi.bios.date: 08/06/2015
dmi.bios.vendor: LENOVO
dmi.bios.version: A6CN58WW
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: VIUU4
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40709 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Lenovo YOGA 3 Pro-1370
dmi.modalias: dmi:bvnLENOVO:bvrA6CN58WW:bd08/06/2015:svnLENOVO:pn80HE:pvrLenovoYOGA3Pro-1370:rvnLENOVO:rnVIUU4:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrLenovoYOGA3Pro-1370:
dmi.product.name: 80HE
dmi.product.version: Lenovo YOGA 3 Pro-1370
dmi.sys.vendor: LENOVO
version.compiz: compiz 1:0.9.13.0+16.10.20160818.2-0ubuntu2
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.70-1
version.libgl1-mesa-dri: libgl1-mesa-dri 12.0.3-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 12.0.3-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-1ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.7.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160706-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-2
xserver.bootTime: Sun Oct 2 22:00:16 2016
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.18.4-1ubuntu6
xserver.video_driver: modeset