Single Phone Number of Multiple Phone Line account not receiving Text Messages

iPhone 11 not receiving short text messages from T-Mobile to a single phone number "XYZ"
Several lines on the T-Mobile account - iPhone 11, iPhone 10 and iPhone 7. All other phone numbers have no issues to date.

The phone number is not on the government no-caller list.

Desire is Not to Port this Phone number to a different carrier.

Issue is not device related. Issue is not SIM card related.

To verify not a phone or SIM card issue with a really solid T-Mobile representative; performed the following:
 Performed factory resets on all phones.
Swapped SIM cards between phones. When other SIM cards (associated with other numbers) were in each phone; short messages appeared with no problem. This was tested with both Wi-Fi on and Wi-Fi off. 
Software is up to date on all phones. 

The issue appears to be associated with a single phone number "XYZ"

Bought a new SIM card. Activated that SIM card with the single phone number "XYZ".
Tested the new SIM card in all three iPhones. The card recognizes network. The card allows phone calls. 

Short messages are STILL not being received. 

T-Mobile states that they have "pending" status on all short messages  including those from T-Mobile on their backend server for the specific phone number. The T-Mobile error message states 'Device' issues.  T-Mobile is stating that the device is for some reason not receiving the messages.  

T-Mobile representative acknowledged by all the actions taken with swapping SIMs, re-setting phones, activating a new SIM that this is NOT a device issue.  This in spite of the error message on their backend server. 

Again, this is associated with a single phone number.

T-Mobile representative suggested half-heartedly that I "port" my number to another carrier.  Said their hands were tied and that yes, the engineering ticket has been updated and they must wait for engineers to respond. Each call extends response time for fixing to another 3 day

Honestly at a total loss here. 
I've tried all the suggestions in T-Mobile feeds and Apple feeds, and performed numerous test cases both with T-Mobile representative and without. All documented with the representative for the engineers. 

Again, this is associated with a single phone number.

Anything else to try?