GF has become increasingly useless as features have been progressively gutted. Today I saw that the Explore option (where you leave the destination empty but specify the dates) now ignores the dates and defaults to 'any time in the next 6 months'. Then you have to go back and fix it for the dates you actually want.
For anything other than vanilla returns or one-ways you should just forget it, and even for those you can no longer rely on them as they withhold results.
Google basically took the 30 pieces of silver and turned a decent tool into a big heap of useless.