I have that airplane and the BVM electric gear in it, but since you have Down and Locked I'm not sure how similar the programming/setup is. Mine uses a Xicoy controller.

I suspect it's a relatively simple programming issue in the controller and not an issue with the nose unit itself. With the Xicoy controller, each door has its own setting for gear up and gear down. Sounds like your nose door is set to stay open on gear down.