I have recently installed android studio and all its update using sdks manager. When i try to start the emulator i can see this:
emulator -netdelay no
I ran into the same your issue, this is what I did that works: My one starts working with Nexus_4_API_25 (tried even with Nexus 6, Nexus 5 and Nexus One none of them was working!!) Create a new ADV from Android Studio ( bare in mind that i didn't allow the new front and rear camera to the new device, so switch them off) So go to Terminal and go to the folder where your emulator is and lists your emulators, my one:
~/Library/Android/sdk/tools/emulator -list-avds
After run your emulator with the gpu hosted on your machine:
~/Library/Android/sdk/tools/emulator -avd Nexus_4_API_25 -gpu host
It will start the emulator and then you can run your app in it. Hopefully this can helps someone else.