Hi Sam,
The LR X1000 will only let approaches be set for the determined airports based on the flight plan. If there are multiple airports in your flight plan beyond 2, then it will only let you pick the approaches from one of them (either the last, or second airport, I don't remember at the moment). If the right airport isn't currently showing for the approaches to activate, make sure there aren't any other airports in the X1000's flight plan.