Microsoft has pushed a new update to Windows 10 build 10130 that fixes an issue causing flyouts for things like notifications not responding to user input. The issue appears to affect flyouts when clicking icons on the taskbar. From Microsoft:
"When you click icons on the taskbar (including Start, Cortana, Network, Battery, and Action Center) in Build 10130 of Windows 10 Insider Preview, the expected flyout might not open."
An annoying bug, to be sure. If you've been experiencing issues with this very thing, you should be able to pull this fix from Windows Update now.