USB microphone not appearing in Storyline audio recording

Here's some thoughts:

Are you using Windows or Mac? What OS version are you on? Are you working on a story file that is actually on a shared network drive? What other programs do you have open at the same time? Are you working in a remote location that could be affected by the current weather systems, or are you in a more stable network environment such as a corporate office? Are you using multiple monitors, and is the story playing on one of the external displays?

And (because this happened to me last week): Are you plugging the mike directly into the laptop/desktop, or attempting to use it through a docking station ("brick") or a shared port (USB multiplier)? And what are the port ratings for the device: USB 2.0, 1.0, etc.?

I had several issues with peripherals last week (including working in Storyline) that were all ultimately resolved by replacing the docking station brick that I had. Apparently there was some internal issue with one or more of the USB drives that arose completely out of the blue.

If none of these troubleshooting steps resolves your issue, I would work with your IT to see if you can narrow this down, but I do not think there is anything in Storyline that is a direct cause. (But I have been wrong before.)