When adding a new xlink to a project, you must select a target changeset to track on the linked repository. When you open the dialog box, the default search query is this:

find changeset where date > '5/27/2020' on repository '<repo_name>@<server_name>:<port>

(today is 6/26/2020)

For some reason it always defaults to only show changesets from less than 1 month in the past. Seeing as xlink is primarily used for reusable, modular code, this means there is almost never any changesets shown. So in order to find the latest changeset you have to click "Advanced" and remove the date clause manually.

Personally, I'm aware of this quirk and I know how to fix it, but this has caused problems in the past for less experienced developers and it pretty much ensures that they will not be able to figure out how to xlink a module without my help.

A better way to do this would just be to show the last 20 changesets or something. Constraining it by date is extremely short sighted (heh) and unnecessarily confusing.