Hey Kurt. I'm Greg, an installation specialist and 8 year Windows MVP, here to help you.
Please run the Recording Sound troubleshooter at Start button > Settings>Update & Security>Troubleshoot.
Right click the volume icon in System Tray at right end of task bar, open Recording Devices, see if the microphone is listed, set it as Default device.
Try rolling back the sound controller drivers in Device Manager reached by right clicking the Start Menu. Choose Sound controller device, then Driver tab, then Roll back if available.
Update the Sound drivers from the PC's Support Downloads web page. While there make sure you also have the latest Chipset, Display, Network, USB and all other drivers, comparing with the version presently installed in Device Manager.
If no newer driver then uninstall the ones presently installed in Device Manager, reached by right clicking the Start Button. Restart PC to reinstall.
When did this behavior begin? If you have an idea you might be able to System Restore back to a point before it began:
http://home.bt.com/tech-gadgets/computing/how-t...
It's possible this was caused by a Windows Update so if nothing above works, go to Settings>Update & Security>Windows Update, check the Installed Updates list for Updates that might have been just installed, try uninstalling them using the Uninstall button present there. Then hide the Updates using the Hide Updates tool downloaded from here:
http://download.microsoft.com/download/f/2/2/f2...
You can also roll back Version 1803 in Settings>Update & Security>Recovery and then hide it until it matures using the Hide Updates Tool downloaded from here:
http://download.microsoft.com/download/f/2/2/f2...
Go over this checklist to make sure the install is set up correctly, optimized for best performance, and any needed repairs get done:
http://answers.microsoft.com/en-us/windows/wiki...
Start with Step 4 to turn off Startup freeloaders which can conflict and cause issues, then Step 7 to check for infection the most thorough way, then step 10 to check for damaged System Files. Then continue with the other steps to go over your install most thoroughly.
If nothing else helps then run a Repair Install by installing the Media Creation Tool and choosing from it to Upgrade Now. This solves many problems and will also bring it up to the latest version which you need anyway and by the most stable method.
http://windows.microsoft.com/en-us/windows-10/m...
But remember that Factory or Upgrade installs are inferior installs which most enthusiasts won't even run because they'd expect endless issues. Consider doing the Clean Install in this link which compiles the best possible install that will stay that way as long as you stick with the tools and methods given:
http://answers.microsoft.com/en-us/windows/wiki...
There is also an automated Refresh that reinstalls WIndows while shedding corrupting factory bloatware, saves your files, but doesn't clear the drive to get it cleanest:
https://www.howtogeek.com/265054/how-to-easily-...
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.