IOS – Incorrect phone number format when dialing from iPhone

• iPhoneXs
• iOS 13.4 (also affected 13.3.x)
• Carrier: AT&T
• e-SIM (no physical SIM)

On a recent trip out of the U.S. I added a 2nd SIM card and a local calling plan (Turkcell) so I could use my phone without incurring roaming charges. All was fine.

PROBLEM: When I returned, I deactivated that plan, and removed the SIM card from the phone. However, the iPhone retained the incorrect phone number formatting on the dialpad screen. See screenshot below for example:

This might seem like a frivolous detail, but it actually slows me down when dialing numbers "manually" since it always looks like I've entered the number incorrectly, skipped a digit or added an extra one, etc. I just want to get it back to the correct format.

Once I hit the green Dial button, the number is correctly formatted, so it's just doing this on the pre-dial screen. See below:

Thing's I've tried:

• Soft resetting the phone (Vol+, Vol-, then press+hold Power until it reboots)
• Changing Language under Settings > Language & Region e.g. from English U.S. to something else and then back again
• Adding / removing additional keyboards
• Turning Roaming on/off
• Turning Cellular Data on/off
• Disabling the cellular line under Settings > Cellular and then re-enabling it
• Calling AT&T and having them "re-provision" my phone
• Updating from iOS 13.3 to 13.4

Things I have NOT tried:

• Going to an Apple Store (they're closed here right now due to COVID-19) ?
• Doing a full Backup / Restore of the phone
• The various "Resets" under Settings > Reset (was afraid to lose my stored passwords/WiFi settings but if anyone thinks that would fix it, I will try…)

Anyone ever see this or know how to fix it?