I wonder if this is a time-out issue. If the AirNav server looks at the GAS database and can't get through for some reason, then it doesn't look again - flagged as "no details"?
This must be an AirNav server issue, as RB searches the AirNav server, not the GAS server direct. As we don't know the logic here, we don't know where it is falling down.
I do have some aircraft that stubbornly refuse to populate - RyanAir B737's in particular!