No Mobile Data on unlocked SM-G935W8 after latest update - Please Help!

[fun_e_mahn]

Hello,
I have a Galaxy S7 Edge – Canadian Edition (SM-G935W8) that I successfully unlocked, and was successfully using it in Thailand with one of their largest providers (True-H) and getting great LTE data connection and speed. However, recently, for the life of me I can’t get any mobile data whatsoever. Please see the below relevant information & any help / input would be greatly appreciated.

• The problem started when I accepted the latest Android System and Security Update over the air. Prior to that I was getting either a “4G” or “LTE” logo beside me signal strength bars. After the update, no more logo, no more mobile data.
• I am able to receive SMS text messages.
• I went through all permutations of Network Modes and Network Operators.
• I created and tried all the published APNs.
• I took it to the provider store and they tried the same without success.
• I downgraded my ROM to the oldest version of Nougat available via Odin. I made sure to flash all components incl. modem and bootloader (clicking bootloader checkbox in Odin).
• When I toggle between Network Modes and Operators, I receive “Registered Successfully” and Time/Date gets auto synchronized.
• I cleared cache & factory reset.
• The one difference that struck me was that I initially had my Canadian SIM (Rogers) in my phone before putting the Thai one in. Now, I lost my Rogers SIM and don’t have the option to experiment by putting it in then the Thai one in again.

Do I need to root?
Something to do with Regions and new Security?

Any help on this would be super appreciated!!

Thanks a ton in advance!!

Cheers!!