I have heard that there is a bug but I want to confirm here.
I have the Max Transit Duo with Verizon sim and AT&T sim.
In WAN Details, the AT&T connection always reports the band/s used.
The Verizon connection, when in LTE-A, never reports the bands - it is absent. It reports frequencies but no bands. In LTE (no aggregation) mode, the band is reported.
If this is a bug, when will it be fixed please?