Brightness hotkeys don't work correctly when booting Ubuntu after Windows 10 is restarted

[disco]

When Ubuntu is booted first, brightness control hotkeys (Fn+F5/F6) work properly:

keycode 232 = (keysym 0x1008ff03, XF86MonBrightnessDown), state = 0x0
keycode 233 = (keysym 0x1008ff02, XF86MonBrightnessUp), state = 0x0

Event: time 1465373197.220356, type 4 (EV_MSC), code 4 (MSC_SCAN), value 92
Event: time 1465373197.220356, type 1 (EV_KEY), code 224 (KEY_BRIGHTNESSDOWN), value 1
Event: time 1465373197.220356, -------------- SYN_REPORT ------------
Event: time 1465373197.281329, type 4 (EV_MSC), code 4 (MSC_SCAN), value 92
Event: time 1465373197.281329, type 1 (EV_KEY), code 224 (KEY_BRIGHTNESSDOWN), value 0
Event: time 1465373197.281329, -------------- SYN_REPORT ------------
Event: time 1465373198.438544, type 4 (EV_MSC), code 4 (MSC_SCAN), value 97
Event: time 1465373198.438544, type 1 (EV_KEY), code 225 (KEY_BRIGHTNESSUP), value 1
Event: time 1465373198.438544, -------------- SYN_REPORT ------------
Event: time 1465373198.499654, type 4 (EV_MSC), code 4 (MSC_SCAN), value 97
Event: time 1465373198.499654, type 1 (EV_KEY), code 225 (KEY_BRIGHTNESSUP), value 0
Event: time 1465373198.499654, -------------- SYN_REPORT ------------

However, brightness control hotkeys behave differently (both are acting as mute button) if Windows 10 was booted first, restarted and Ubuntu is booted next:

keycode 198 = (keysym 0x1008ffb2, XF86AudioMicMute), state = 0x0
keycode 198 = (keysym 0x1008ffb2, XF86AudioMicMute), state = 0x0

Event: time 1465412194.886809, type 4 (EV_MSC), code 4 (MSC_SCAN), value 81
Event: time 1465412194.886809, type 1 (EV_KEY), code 190 (KEY_F20), value 1
Event: time 1465412194.886809, -------------- SYN_REPORT ------------
Event: time 1465412194.893971, type 4 (EV_MSC), code 4 (MSC_SCAN), value 81
Event: time 1465412194.893971, type 1 (EV_KEY), code 190 (KEY_F20), value 0
Event: time 1465412194.893971, -------------- SYN_REPORT ------------
Event: time 1465412195.386644, type 4 (EV_MSC), code 4 (MSC_SCAN), value 81
Event: time 1465412195.386644, type 1 (EV_KEY), code 190 (KEY_F20), value 1
Event: time 1465412195.386644, -------------- SYN_REPORT ------------
Event: time 1465412195.393592, type 4 (EV_MSC), code 4 (MSC_SCAN), value 81
Event: time 1465412195.393592, type 1 (EV_KEY), code 190 (KEY_F20), value 0
Event: time 1465412195.393592, -------------- SYN_REPORT ------------

What is expected is that brightness hotkeys behave as brightness hotkeys in both cases.

Description: Ubuntu 16.04 LTS
Release: 16.04

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: udev 229-4ubuntu6
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CurrentDesktop: Unity
CustomUdevRuleFiles: 45-opencbm-xu1541.rules
Date: Wed Jun 8 21:05:39 2016
EcryptfsInUse: Yes
InstallationDate: Installed on 2016-04-28 (41 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 002: ID 138a:003f Validity Sensors, Inc. VFS495 Fingerprint Reader
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: HP HP ProBook 470 G3
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-22-generic.efi.signed root=UUID=b76cac24-b495-450f-a0e1-065b6a6a9ed4 ro quiet splash vt.handoff=7
SourcePackage: systemd
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/25/2016
dmi.bios.vendor: HP
dmi.bios.version: N78 Ver. 01.07
dmi.board.name: 8102
dmi.board.vendor: HP
dmi.board.version: KBC Version 40.03
dmi.chassis.type: 10
dmi.chassis.vendor: HP
dmi.modalias: dmi:bvnHP:bvrN78Ver.01.07:bd01/25/2016:svnHP:pnHPProBook470G3:pvr:rvnHP:rn8102:rvrKBCVersion40.03:cvnHP:ct10:cvr:
dmi.product.name: HP ProBook 470 G3
dmi.sys.vendor: HP