XM cannot BYOD brand new unlocked Pixel 3a phones

TLDR: don't buy a Pixel phone thinking you can use it on XM; the IMEI won't validate with XM, even though Verizon's website validates it.

 

I was stoked that XM offers BYOD for the entire Pixel series now. https://www.xfinity.com/mobile/support/article/bring-your-own-phone-details

 

I purchased a brand new Pixel 3a direct from Google Store online, unlocked. Google plainly states that it works on all cell networks; there is only a single model of each Pixel phone, there are no "Verizon" or "ATT" versions, and all of them sold on the Google Store are SIM-unlocked. https://support.google.com/pixelphone/answer/7107188?hl=en

 

Arrived, turned it on, attempted to BYOD, and the IMEI was rejected.

XM IMEI result screenshot (my IMEI removed), fails: https://i.imgur.com/iebwfPyl.jpg

 

Talked all the way up to XM tier 2 support; they said that the phone "is not compatible with Verizon." The agent said they contacted engineering, who said the same thing, and ended the call.

 

I went to the Verizon site and put in my IMEI for BYOD with them, and Verizon said it was fully compatible and offered to activate it on their Verizon network.  It says: "Awesome, your Google PIXEL3AXL-NVZW is a perfect match for our network."

Verizon IMEI result screenshot, validates: https://i.imgur.com/ckTKjH9.jpg 

 

(UPDATE: Check a few posts down; I checked, and all other providers also accepted my IMEI.)

 

So what's going on? I don't want to just do a SIM swap, because I'll loose VoLTE on my phone, I'm needing to add a new line and I bought a new phone I can't use.

 

If someone from XM can actually help with this, please reach out to me.