I'm having exactly the same same problem . I go to 'My Products' and I don't even see the my content partner, that allows me to access Gamepass. I went with the Fibre 900 so got 12 months gamepass in the deal.
I did contact customer service last Friday, and they said it should've fixed within 5 days, but as of yet I still have to option to access Gamepass via My Products.