Hello,
I'd like to start off by saying that although I'm not a tuning expert I do have some experience with tuning timing, fuel, etc.
I recently finished a 4.3 to 5.7 swap into my 1999 chevy blazer with a black box to 0411 pcm swap, other than that the motor is all stock. Truck runs good and only codes that I have are for P1336 which is because it needs a crank relearn and a code for the evap.
I started datalogging the truck and it runs good, however the timing starts at 16* on startup and does not move at all regardless of map reading, throttle position, rpm, it just doesn't change it stays at 16*.
I tried adjusting the main spark tables and it does nothing, zeroed out the iat, ect, and all other factors along with zeroing out burst knock, egr, idle overspeed/ underspeed, and just about any table that affects timing and it does nothing.
If I command timing through the datalogger controls it changes, and if I put the minimum spark advance table in the tune higher than 16 it will hold the number I enter, but if the minimum spark advance is lower than 16 it defaults back to 16.
I use the same laptop and everything for my 0411 swapped turbo 4.3 and the timing in it works perfectly ranging from 30+ Into the low 10s so I don't think it's anything in my configuration.

Is there any table or something I'm missing that causes timing to lock like this? I don't get any KR while driving or anything but like I said the timing will not change. Any help is appreciated.
Also I have tunes and logs but I'm posting this from my phone, if needed I can post them later though.