Sounds to me more like a user/group issue in your AD if its only pulling up certain groups/users. That would mean it's communicating properly.... just not fully.
Why not update the firmware on both of them to be the same? That makes the most sense to me.
I currently have the same set-up, but I'm at 1.52 for both. At your own descretion I would look into updating your firmware.
Cheers,
Jake