Truck Forums - Keyless entry exits programming mode before I can program the remotes

I have a unique problem I could not find an answer for.

2006 Chevy 3500 Silverado Crew Cab Flatbed, 6.0, Auto
Power Locks
Manual Windows
Factory Passlock security system

I ordered 2 new remote transmitters, since none came with the truck. When I attempt to program them, the system exits programming mode 3 seconds after entering. I tried the normal steps to get into programming mode, but every time it just exits by itself. I am wondering if I need a new lock module or BCM, or if there is something I can fix. The system cycles the locks and beeps the horn like its supposed to, but 3 seconds later it exits programming mode. I have tried disconnecting the battery overnight to no avail. I looked everywhere but couldn't find a similar issue. If anyone has faced the same problem please let me know how you fixed it!