VoLTE on Secondary Line - Dual SIM Issues

Background:

iPhone 11 Pro - Unlocked

AT&T Service on eSIM (Primary Voice and Data)

Xfinity Mobile Service on Physical SIM (Secondary Voice and Data)

Cellular Data Switching Enabled on both Lines.

VoLTE enabled on both lines.

WiFi Calling Enabled on both lines.

iOS 13.3.1

Phones being called are all iPhones

Dual SIM XS Max (T-Mobile Primary eSIM / Xfinity Secondary Physical)

iPhone SE Xfinity Mobile

iPhone 6 Plus Xfinity Mobile

I’ve been encountering issues which seem to be related to VoLTE or some type of Data Network Registration delay or error when making calls on my Secondary.(Xfinity Line) Theses issues do not occur all of the time but often enough to take note. The issue manifests in a few different ways. I’ll make a call from my secondary( xfinity line ) to another number on the xfinity network while I am connected to the primary cellular network. When this happens my AT&T 5Ge icon drops and the Xfinity LTE icon pops up in the corner. ( I expect this ) The phone is dialing/ringing and from here i’ve noticed 3 outcomes.

1.). If everything works as it’s supposed to the call connects, the voice connection is notably an HD connection, the LTE icon persists in the upper right corner of the phone and browsing and other internet traffic passes while on the call.

2.) The phone dials and rings the other phone and when the other user attempts to pick up the Call is disconnected and the receiver gets the call failed pop up.. Depending on how quickly they acknowledge the call failed message the calling phone may actually retry the call(as I believe it fails over) and succeed but not as an VoLTE call as the LTE icon disappears and the voice quality is notably not HD and no Internet traffic passes.

3.). The phone dials and rings the other phone for a few rings and then the LTE icon disappears, (ring sound quality drops) and the call is sent over the regular cellular network, I’m guessing the CDMA network as it’s Xfinity/Verizon. Again, no cellular data during the call and no HD voice.

When the LTE icon does disappear I’ve attempted to make a few other calls to see if it’s just an initial negotiation delay but subsequent calls seem to just go over the regular cellular CDMA network and the LTE icon just disappears or maybe does not even come up after the initial call. I’ve been able to fix this by toggling the phone into and out of Airplane mode and then attempting to make the call again and then the LTE icons stays up in the corner and everything works as expected again until it doesn’t again.

I realize that this is probably not a very typical phone configuration with the dual SIM setup but figured I would ask the forum to see if anyone else has experienced something like this and if anyone knows why this is happening and if there is a more permanent way to fix this.

Thanks!