Do you see your "Virtual Switch" information under: Control Panel\\Network and Internet\\Network Connections? If not, you can try to recreate your "Windows Phone Emulator Internal Switch" again from Hyper-V to see if that resolves your issue. Try these steps below:
1.) Open Hyper-V
2.) Shutdown any existing configured Phone emulators.
3.) Click on "Virtual Switch Manager"
4.) Click on the "Windows Phone Emulator Internal Switch"
5.) Remember what the settings are displayed there (because you will delete it and recreate it)
6.) Delete the existing "Windows Phone Emulator Internal Switch" by clicking "Remove"
7.) Click "Apply" and "OK"
8.) Re-create the "Windows Phone Emulator Internal Switch" by clicking the "New virtual network switch" and use the same settings you remembered in Step 5.
9.) Then try to F5 from Visual Studio - which should configure a new emulator on the right virtual switch.