Are you sure you were on a Gogo-equipped aircraft? (Where the wifi network is named "gogoinflight".) I have been using my pass on both carriers for months now without issue.

However the Gogo pass isn't, and will never be, valid on ViaSat-equipped aircraft (Where the wifi network is named "virgin america".) Those planes should be re-equipped with Alaska's Gogo 2ku satellite solution in the next 12-18 months, and will then be usable with the pass.

I have found the last comment on this thread to still be a fairly reliable way to guess which equipment you'll have: How do I Figure Out Which Wifi is on a Flight and the Pricing?