Same issue. Additional details. Using a Qualcomm Snapdragon X7 LTE-A (Sierra Wireless EM7455) module in my Lenovo laptop. Has worked since day one of getting laptop nearly a year ago . AT&T is trying to put blame on Qualcomm for not setting up the IMEI as being hotspot capable.
This is a real issue that needs to be resolved. Or me an my multiple unlocked and/or un-branded phones, tablets & computer will be finding a new service provider.