make sure you typed the correct device phone number, including country code and area code.
In some counties there may be some delay with the SMS, wait 5 minutes and check again.
You can enter the settings and click “Reset Registration”. You will be asked to re-enter the phone number and new SMS should be sent.
if all the above did not help, it could be that SMS in your area is blocked for cloud service provider,
you can try the new feature "receive code by call",you will receive an automatic call in which the code will be provided to you by voice.
if this still not solved your issue, please schedule date and time with our support using Calendly (https://calendly.com/shayg/flashing-device)  and we will provide you the code manually.