If you are trying to use add/edit/delete functions and do not receive an Authentication Code, please ensure that:
You have network coverage in your area
Your mobile number on your profile is correct and verified, you can confirm that under Settings >> Manage Profile >> User Settings
Sometimes, there could be network delays and you may not receive the Authentication Code immediately. The Authentication Code is valid for 5 minutes.
You might be interested in the following questions
Which add/edit/delete functions require Two Factor Authentication Code?
Which add/edit/delete functions require Two Factor Authentication Code?
How can I verify my mobile number to receive Two Factor Authentication Code?
I am unable to verify my mobile number; how do I receive Two Factor Authentication Code?
My mobile number has changed; how do I update it to receive Two Factor Authentication Code?
Do I have to enter Two Factor Authentication Code every time I access add/edit/delete functions?
I received multiple Authentication Codes, which one should I use for add/edit/delete functions?