Apple Two Factor Authentication: why verification code popup don't display? I turned on Two Factor Authentication mode, it worked very well. But yesterday, I reinstalled my Macbook, and iPhone, verification code popup don't automatically display when I login new device. I must get code through text message, or manually getting verification code from iCloud setting. I logged both iPhone, and Macbook, but all don't show popup (I also try to log from another pc but same result).

I’m using Mac OS 10.12.3, and iOS 10.2.1

I think two cases:


It's a problem occurred when I reinstalled my device.
Someone (may be a "hacker") controlled my apple ID and my devices. (I'm worry about this!)
When you restore a device, it is removed from the trusted device list in case you want to sell it. Here's how you can add the iPhone back to the list:

Go to appleid.apple.com and sign in. 

Under security, go to Trusted Devices. 

Refresh devices then follow directions to confirm your device. 

Remove your unused versions of devices. 

You will only be able to receive codes on your iPhone, not your mac.