As such, those who are on the Preview and who still want the Lumia Cyan update need to downgrade their OS first. This is still Microsoft's position on the situation.

Earlier today, AT&T announced that their Lumia 1520 is now receiving the Lumia Cyan and Windows Phone 8.1 updates. However, it quickly became evident that those with the Preview for Developers installed on their Lumia 1520s did not have an update, but those with Windows Phone 8.0 did. The reason for the discrepancy is Microsoft has put on hold updates for those running the Preview.

The original issue stems from those who were using the Preview for Developers version of Windows Phone 8.1 and who have BitLocker encryption enabled (through their employer). Although those affected are a small minority of users, when they installed the official 8.1 update, it caused the phone to lockup. As a precaution, Microsoft halted the Preview program for everyone. In a previous statement to Windows Phone Central, Microsoft advised:

"We are currently investigating the issue. We have paused delivery of the update to customers using the Preview for Developers, and will resume once a fix is in place. Customers whose phones have been affected should use the Nokia Software Recovery Tool to return your Lumia to a normal commercial software state before downloading the Lumia Cyan update. More information about the tool can be found at www.nokia.com/support/recovery-tool."

Microsoft is sticking with that statement today, and it applies to those with the Lumia 1520 on AT&T who would like to update now to Lumia Cyan. Presumably Microsoft will eventually push out a fix for the Preview program to allow carrier updates to continue, however, as of today they have no ETA on that update or anything further to add. In other words, it could be days or weeks.

This situation is not limited to Lumia 1520 owners on AT&T, as it applies to anyone who is on the Preview for Developers version of the OS and are eligible for the Lumia Cyan update.

What to do next

Those people wishing to grab the Lumia Cyan update today for their Lumia 1520 need to downgrade the OS to Windows Phone 8.0 first. The option to not downgrade is up to the user, but Microsoft is advising the returning the phone to 8.0. Users can take a wait-and-see approach if they desire.

Before proceeding, you are advised to back up your device first (Settings > Backup > App + settings > Back up now) before starting the restore process.