Windows 7 - Missing Date Popup

I installed a new 4k monitor, then ended up returning it. Somewhere along the way though, my Windows 7 was changed in such a way that I no longer get a calendar popup when I click on the date/time in the task bar such as shown in this sample screenshot:



Now, when I click on the clock in the bottom right, nothing happens. Is this a configuration issue or is my version of Windows 7 Pro hosed?

What happens if you open Date and Time from Control Panel?

Nothing exciting, works as normal.

Alright, my guess is that it is opening but at some odd location off-screen, possibly a bug of some sort.

Would you try:
- safe mode
- another user account (create one to check and delete later)

No luck. Ended up doing a clean reinstall of Windows because of other, similarly random issues.