With weekly reset, Bungie ended the 2 week open access expansion event which means players now only have access to the content they have purchased. If you do not own The Final Shape on the platform you're attempting to use Prismatic on then you will not be able to use it. If you do own The Final Shape on that platform then try [url=https://help.bungie.net/hc/en-us/articles/360049196071-Accessing-and-Restoring-Licenses-to-Destiny-Content]restoring licenses[/url]. If that doesn't work then contact your platforms support team to look into it.