Simply a followup - within the last couple days I've logged into ATT fresh and the display now shows my account information correctly except for the missing NEXT payment information. The display now is the same whether JUST logged in or just logged in and after a simple page refresh, so there is no anomaly anymore.
I'm assuming the NEXT payment/information will show up after the next due date passes and that the bill will increase to where I thought it would be back on December 6th due to the added cost of changing a basic line to a smartphone line and the NEXt payment for the smartphone on that line.
As such, this particular thread is "resolved".