I was told that BYOD for Androids does not support VOLTE. Which some people call HD Voice and also enables you to talk on your phone and use your data at the same time. My current phone Samsung Galaxy S8 had no issues doing this on AT&T but the option is not present on Xfinity Mobile. Support was not going to escalate my issue but eventually did. Here is what I was told.
When I tried this (sim swap) with my VZW Moto Z Droid 2 years ago, everything (including volte) worked for 2 billing cycles and then volte was shut off by XM. How long have you been using your Moto XPE with XM and is everything still working?