Hey there,
This is a known issue. Bungie is aware and actively investigating.
[quote]• Allegiance Quest: We are investigating an issue where players cannot progress past Spider's Black Market in the Allegiance quest.[/quote]
https://www.bungie.net/en/Forum/Post/252327934/0/0/1
Stay tuned to official Bungie sources for updates on the matter.
Sorry to hear any inconvenience.