Thank you for your continued support. Per your recommendation above I pulled the SIM card, rebooted, dialed the code in Google Dialer and same result.
From what I'm observing is the behavior acts like that feature is being blocked as right after I type in the last the character "*" the code string disappears and nothing happens. Like it try to do something but doesn't. I can type in *#*#27262826#*# ######## and will allow to type in unlimited characters but if I type in *#*#27262826#*#* the character string disappears.
@kangi26 - I flashed my phone per your recommendation above and still having the same result. Crazy. Do you think I should try putting in the ATT SIM that came with the phone and try or does that not make any difference?