No tracking #'s for First Class Envelopes

Hello -

We ship many of our products via USPS FIRST CLASS using 'thick envelopes'. These fit the thick/large envelope dimensions that USPS requires.

While using the system with stamps.com, we were able to receive tracking #'s for each first class envelope shipped

We just moved over to endicia.com and now First Class tracking numbers are not available. Also, the label looks much different than priority shipments. A number is automatically uploaded to our sales channels but this is not a tracking number.

How do I fix this and get tracking information for First Class 'thick envelope' shipments?

Thanks