Need Help With DDC Controller Disappearing On Me

I am having issues right now with the DDC controller disappearing on me. Every time I go to a specific consist and click on the locomotive in a route that I am running. The DDC controller disappears on me. Can someone tell me how I can fix this issue? Thanks in advance.
Surveyor > edit Session rules (button right of quick drive) > highlight Driver Setup > Edit > Add another driver (may need to scroll down as its at the bottom of the list of any existing Drivers) > select from list > click vehicle > select a loco. Repeat for each loco you want to use.
One more question if you don't mind me asking. When I start the route. I am at a different consist in the game. Therefore, I have to fly through the route. Is there a way that I can change the camera view from the consist that I have right now to the consist that I want to run on another end of the route. I hope you understand what I am saying here. Thanks.
Clicking on the driver image in the bottom left corner will bring up a list of drivers down the left side of the screen. Clicking on any of these will move you to that consist. If the list is long there are arrows at the top of the list to move the list down/up.
Here is what I don't understand. On the Mojave sub T12 edition. I have no problem going from one train to another without losing the DCC controller, But when I try to do it on the Quahog Subdivision route. It wont work at all. Why will it work on one route and not work on another? Right now, I am still having problems with losing the DCC controller when I try to do it on the Quahog route.