That means the code/path you used was one you had already done. There is no time restriction on getting the lore. There are numerous sites that have the entire list of codes, and you can just run through them one after the other. When you finish one, walk towards the grave, and you'll get teleported outside. There will be a pillar near the doorway, which after a few seconds, will allow you to reset the corridors of time, and do a new code. There's no need to limit yourself to one per hour. Find a site with a list, and run through them all, and you should have all the lore by the end. [url=https://www.polygon.com/destiny-2-shadowkeep-guide/2020/1/14/21065781/corridors-of-time-quest-traverse-explore-lore-page-timeliest-vault-codes]Here's the one I used.[/url]