Trade in device dropped in usps but wont show status update

I purchased a new iphone under trade in promo program. I returned my old phone( basically 2 months old) packaged using the tmobile provided return label that was going to Asurion.

I dropped the package at USPS and kept the smart label tracking number. It has been 14 days but the status of package is not updated on usps. It says 
Label Created, not yet in system.

  At this point, I have no clue how should i track my package. I received a final reminder email saying I have until Dec 18 to return my device or I will loose promo credits.

  I see lots of people have had issues with device return exactly same way and have contacted usps and tmobile both regarding the same but no feedbacks.

Please advise next steps.