2025 GMC Sierra 2500 L5P high idle

Hello all, I have a 2025 GMC Sierra 2500 L5P that I had a BD Diesel high idle kit installed. The vehicle will go into limp mode after I deactivate the high idle. The shop is baffled as to why and quadruple checked all connections are in correct spot and securely connected. BD is also baffled as they have never got a complaint like this. Has anyone dealt with this and if so what was the fix? Note I know these trucks have the ability to use high idle however I called all the dealerships in my state and not one can/will flash my system in order to activate it. This is why I chose to get the BD kit