Why can I not choose the microphone icon in Snap Core First when editing a message on a button?

It's possible that access to the microphone in Snap was turned off in Windows.

1. Select the Windows start menu.
2. Select Settings.
3. Enter Microphone in the search field.
4. Select "Choose which apps can access your microphone".
5. Scroll down.  Under "Choose which apps can access your microphone", make sure Snap Core First is turned on.