Screen doesn't lock on suspend when cinnamon menu is open

When I close the lid of my HP Pavilion dv6-6095sg laptop with Linux Mint Cinnamon 18.1, it usually suspends and locks the screen. When I open the lid again, it asks for my password.

However, when the Cinnamon Menu ("Cinnamon-Hauptmenü") is open and I close the lid, the laptop suspends but doesn't ask for my password.

I can reproduce this bug and a reboot didn't fix it.

Thank you for adressing this bug!

Here are my hardware details:

System: Host: hp Kernel: 4.4.0-66-generic x86_64 (64 bit gcc: 5.4.0)
           Desktop: Cinnamon 3.2.7 (Gtk 3.18.9-1ubuntu3.2) dm: mdm Distro: Linux Mint 18.1 Serena
Machine: System: Hewlett-Packard (portable) product: HP Pavilion dv6 Notebook PC v: 058F110000244610000620100
           Mobo: Hewlett-Packard model: 3388 v: 10.31 Bios: Hewlett-Packard v: F.1B date: 10/05/2011
           Chassis: type: 10
CPU: Dual core Intel Core i5-2410M (-HT-MCP-) cache: 3072 KB
           flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 9179
           clock speeds: min/max: 800/2900 MHz 1: 801 MHz 2: 806 MHz 3: 803 MHz 4: 803 MHz
Graphics: Card-1: Intel 2nd Generation Core Processor Family Integrated Graphics Controller
           bus-ID: 00:02.0 chip-ID: 8086:0116
           Card-2: Advanced Micro Devices [AMD/ATI] Whistler [Radeon HD 6730M/6770M/7690M XT]
           bus-ID: 01:00.0 chip-ID: 1002:6740
           Display Server: X.Org 1.18.4 drivers: ati,radeon,intel (unloaded: fbdev,vesa)
           Resolution: 1366x768@60.04hz
           GLX Renderer: Mesa DRI Intel Sandybridge Mobile
           GLX Version: 3.0 Mesa 12.0.6 Direct Rendering: Yes
Audio: Card Intel 6 Series/C200 Series Family High Definition Audio Controller
           driver: snd_hda_intel bus-ID: 00:1b.0 chip-ID: 8086:1c20
           Sound: Advanced Linux Sound Architecture v: k4.4.0-66-generic
Network: Card-1: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
           driver: r8169 v: 2.3LK-NAPI port: 4000 bus-ID: 07:00.0 chip-ID: 10ec:8168
           IF: eno1 state: down mac: <filter>
           Card-2: Broadcom BCM4313 802.11bgn Wireless Network Adapter
           driver: bcma-pci-bridge bus-ID: 0d:00.0 chip-ID: 14e4:4727
           IF: wlp13s0b1 state: up mac: <filter>
Drives: HDD Total Size: 250.1GB (6.1% used)
           ID-1: /dev/sda model: Samsung_SSD_850 size: 250.1GB serial: S21PNXAGA29876Z
Partition: ID-1: / size: 89G used: 11G (13%) fs: ext4 dev: /dev/sda5
           ID-2: swap-1 size: 4.24GB used: 0.00GB (0%) fs: swap dev: /dev/sda6
RAID: System: supported: N/A
           No RAID devices: /proc/mdstat, md_mod kernel module present
           Unused Devices: none
Sensors: System Temperatures: cpu: 51.0C mobo: N/A gpu: N/A
           Fan Speeds (in rpm): cpu: N/A
Repos: Active apt sources in file: /etc/apt/sources.list.d/geogebra.list
           deb http: //www.geogebra.net/linux/ stable main
           Active apt sources in file: /etc/apt/sources.list.d/google-chrome.list
           deb [arch=amd64] http: //dl.google.com/linux/chrome/deb/ stable main
           Active apt sources in file: /etc/apt/sources.list.d/google-talkplugin.list
           deb http: //dl.google.com/linux/talkplugin/deb/ stable main
           Active apt sources in file: /etc/apt/sources.list.d/official-package-repositories.list
           deb http: //ftp-stud.hs-esslingen.de/pub/Mirrors/packages.linuxmint.com serena main upstream import backport
           deb http: //gd.tuwien.ac.at/opsys/linux/ubuntu/archive xenial main restricted universe multiverse
           deb http: //gd.tuwien.ac.at/opsys/linux/ubuntu/archive xenial-updates main restricted universe multiverse
           deb http: //gd.tuwien.ac.at/opsys/linux/ubuntu/archive xenial-backports main restricted universe multiverse
           deb http: //security.ubuntu.com/ubuntu/ xenial-security main restricted universe multiverse
           deb http: //archive.canonical.com/ubuntu/ xenial partner
           Active apt sources in file: /etc/apt/sources.list.d/owncloud-client.list
           deb http: //download.opensuse.org/repositories/isv:/ownCloud:/desktop/Ubuntu_16.04/ /
           Active apt sources in file: /etc/apt/sources.list.d/skype-stable.list
           deb [arch=amd64] https: //repo.skype.com/deb stable main
           Active apt sources in file: /etc/apt/sources.list.d/webupd8team-java-xenial.list
           deb http: //ppa.launchpad.net/webupd8team/java/ubuntu xenial main
           deb-src http: //ppa.launchpad.net/webupd8team/java/ubuntu xenial main
Info: Processes: 298 Uptime: 4 min Memory: 471.1/3898.7MB
           Init: systemd v: 229 runlevel: 5 default: 2 Gcc sys: 5.4.0
           Client: Unknown python2.7 client inxi: 2.2.35