I had your same problem and after many attempts resolved it this way:
- Deactivate Hyper-V (and restart computer);
- Go in the Device Manager and open the Network Adapters, here uninstall everything with the name "Hyper-V...", this will allow us to reactivate Hyper-V without any conflict;
- Enable Hyper-V (and restart computer);
Finally launch the emulator (if it is the first time you launch it you will have to wait 5-10 minutes, so be patient and wait for it to load all apps it need).