I'm confused by your statement. You have the auto parking brake disabled but the parking brake still engages when you park. Do you have to manually release it when you start the truck? What is the purpose of the setting if it is going to always engage anyway? Do you maybe have a failure in the system? I have had mine turned off and I don't hear (or feel in the brake pedal) that the parking brake engages.
On my Limited, if I enable the Auto Park Brake feature, it automatically engages the parking brake whenever the truck is put into P. This happens even when the engine is running - you can hear it. When I have it disabled, it seems to still engage the parking brake automatically about 60-90 seconds after the truck is shut off but by then I'm already out and don't care.
The difference is automatically engaging the parking brake EVERY time it's put in P, or just ~90 seconds after shutting off (in P).
In either case, you don't have to manually disengage the parking brake. Simply shifting to D does it for you. Due to this, I've not really cared what it's doing. I think it's not supposed to work this way but I've yet to find the "behave" setting in Uconnect.