Hey there!
You have to finish three quests before you can get the Bastion Quest:
- "Recovering the past"
- "An Impossible task"
- "Completing an Impossible task"
This should grant you the seasonal Triumph "Saintly Savior". Once you redeem it, you should be able to get the Quest from Saint-14.
Please do not add unneeded things like polls to your questions. Thanks.
Please provide a screenshot of your interaction with Osiris and with Saint-14. It would also help to see your quest page.