Why doesn't AwesomeWM recognize all of my modkey keypresses when using an external keyboard or how can I fix it?

I'm using awesome v3.5.6 on a ThinkPad Edge e440 with a mostly stock configuration in awesome (titlebars enabled, some layouts omitted, and the taglist omitted from the wibox). I have a Logitech G110 keyboard connected directly to the laptop's USB port.

modkey is still default at Mod4.

Everything works correctly using the laptop's built-in keyboard.

Using the external keyboard, Awesome doesn't recognize that my modkey is pressed when used in combination with other keypresses, such as modkey+enter to open terminal or modkey+r to open the run box.

Using the external keyboard, AwesomeWM does recognize that I'm pressing modkey when I click on a titlebar, such as to resize or move the window.

I do use QuickSynergy, and the problem exists with and without it.

I have used the same keyboard on desktop computers with earlier versions of awesome and it worked correctly in those setups.

xev does not respond when i press my mod4, and it shows no KeyPress or KeyRelease event. yet I can resize the xev window by holding down mod4, right clicking the titlebar, and then moving the mouse. xev does not output a KeyPress event when I do this.

I've spent some time researching it, and I'd really like to know a workaround or a solution, short of those I'm interested in understanding why so that I can seek a solution on my own or elsewhere.