@TravisDaDrunk simple answer, somehow they messed up the guest pass generator for several months
"June 2016 Update:
For several months premium members were not automatically receiving 48-hour guest passes to give away every month. However, per /forumtopic-943115/guest-pass-inquiries-update, guest passes are now up and running again. "
they also added a limit of 10 passes that a member can redeem per 6 months to avoid abuse (fixing the abuse might also have something to do with why they did not work )
"Just a clarification on the 10 passes issue:
There is now a limit of 10 guest passes per 6 months. That means that
you have 10 guest pass charges and each one has a cool down of 6 months."