Doesn’t show up on my main account but is there on an old Xbox account
Is your main account restricted by chance? For instance, if it was part of an account that had family sharing enabled that would likely restrict access to that. There could be a couple of other account based settings that would limit your access to user generated content.
However, if you can't find anything just try refresing your XB1 account. You can do that by removing the account from the Xbox and adding it back again. This doesn't cause any data loss, but will often fix a variety of account based issues.
Let me know about all of that. Thanks.