Have you checked with Navigraph for a solution?
As far as I know, Captain Sim's 777 FMC uses the default MSFS B747's FMC (or at least the same data it uses), so I assume that it accesses the AIRAC installed by Navigraph, so if it isn't installed correctly, then it won't be seen (i.e. if the default 747 sees/accesses the Navigraph AIRAC, so should the CS 777s).