I've noticed BGL routed objects are not loading fully on the initial load of a flight. This used to be an issue with the very early sim updates but I thought it had been resolved (unless I was imagining it).
After adding some 40+ SimObjects around part of our scenery I started a flight and only 14 loaded in.
Changing the time in the sim by a few minutes seemed to give the sim enough of a 'kick' to reload the objects in fully.
It looks like the sim engine thinks everything is loaded in before it's complete.
SFSimsDev