I activated the Two Factor Authorisation at iCloud. Now, when I try to sign in at some Apple Service, I am getting the a message that a message was sent to my trusted devices with a code I have to enter.
But, nothing happened. Never. I have to click on "Try again" and choose "Send Message to PHONE_NUMBER"
After that, a message with the code gets send to my iPhone, I type in the number and it works.
But, nowhere the code is getting displayed. Neither on my Mac or my iPhone. It just works via Message.
Best Answer
There are a view things you should check:
1) Are both devices marked as 'trusted' in icloud.com (login, go to settings and see 'my devices'.
2) You have to be signed in with both devices with your iCloud account. Did you check both are correctly activated.