There are several possible reasons why this might have happened:
1. Your mobile number might have been entered incorrectly
2. Your mobile network operator might be taking a longer time than usual to send the TAC code to you, try clicking on the "Did not receive?" button and wait for a while longer
Here are some troubleshoot steps that you can try in order to resolve the issue:
1. Please ensure that SMS from shortcode is not blocked in your mobile device or by your telco provider.
2. Please confirm that you have a stable mobile connection. We highly advise you to switch between WIFI and mobile data and retry requesting for TAC code again.
3. If you have changed your mobile number, please note that the OTP code will only be sent to your old mobile number if you are signing in from a new device or attempting to reset your password.
If the problem persists, please submit a request email at https://support.myboost.com.my/hc/en-us/requests/new