Canadian iPhone "No Service" when Verizon SIM is Inserted

I have a Canadian Unlocked iPhone 6S Plus (verified Unlocked via GSX IMEI check). When inserting a Verizon SIM card in to test, the top left corner of the device will initially show “Verizon” and bars. However, after a minute, it changes to “No Service.”

In settings, the carrier is shown as Verizon 40.0. In Cellular it also shows Verizon.

Any idea why this is happening? Is it a hardware issue?