iPad Pro 10.5 only showing 4G not LTE on AT&T

I have a new iPad Pro 10.5 + Cellular running iOS 10.3.3 (14G5047a).

I swapped the SIM in from an old iPad Mini 2 and when I first put it in, it showed LTE service. But when the AT&T rep updated the IMEI to match the iPad's and had me reboot it, it came back showing 4G. I am in an LTE coverage area and all my other iOS devices show LTE sitting right next to this device.

I've checked that LTE is enabled under:

Settings->Cellular Data->Cellular Data Options

I've had AT&T re-send the activation.

I've tried doing:

Settings->General->Reset->Reset Network Settings

Settings->General->Reset->Subscriber Services->Reprovision Account

Settings->General->Reset->Subscriber Services->Reset Authentication Key

None of these worked.

I swapped a SIM in from another family member's iPad Mini 4 that shows LTE on it and it only shows as 4G. It definitely isn't just a display issue because if I run a speed test over cellular, I get 1/10 what I see on my iPhone 7 Plus and if I disable LTE on the phone (and it switches to show 4G) the test results are about the same.

I'm contemplating backing up the iPad and restoring to see if that makes a difference since it *seems* like it might be a software setting issue on it (despite everything looking correct in Settings) at this point but I'd hate to have to go through all that.

Anyone have any ideas?