Same with me. I literally bought Lightfall and ALL the other expansion packs 20 minutes before the unexpected maintenance issue and now all my DLC is gone. I checked and my Microsoft account shows the purchases being completed and everything. Xbox support recommended I request a refund and just repurchase everything. That method concerns me a bit so I'm hoping Bungie figures it out on their end soon and just reinstates the licenses.

same thing happened to me, turns out xbox gaming services are having an issue. the issue has been present over 24 hours. my friend gifted me lightfall deluxe on microsoft store because my steam just will not work at all to log in to d2. i logged in yesterday, did like 5 hours worth and bungie brought the game down. woke up today expecting to pick up where i left off but now microsoft store says i dont own the dlc. https://support.xbox.com/en-US/xbox-live-status

Assuming you have installed the add-ons (or they automatically pre-installed), you might also have to look in your email for a code to input at the xbox.com site or at the store in your console. My code came from sendowl.com with a subject line "Digital Products for Order [ordernumber]". There will be a link in the email to a PDF that will have your digital code. I pre-ordered and that tripped me up. I hope this helps. Not sure if this is your issue, but it was mine.