I get live Short Term Fuel Trim readings on both bank 1 and 2 and i get a reading for the Long Term Fuel Trim on bank 2, but bank 1 simply is blank. It doesnt show 0 or any #, its just blank.

2013 Silverado 5.3 2/ 128k miles.

Check Engine light with codes P015B and P015D prompted me to look at fuel trims. I'm curious why bank 1 wouldnt give a reading? Rebooted my laptop, unplugged the MPVI 2 and resecured it. Turned engine off and on. It works fine on my 2010 camaro, but for some reason this truck isnt giving a reading for LFTF Bank 1.