In Oracle Report you can not link query blocks on items when you see this No-Link Item:

Cannot implement column link for this detail SQL query. Converting to group link.

This means you can link block, but you can not link specific item as you would usually like to do.
It seems there’s somethin special in this query. When trying to link two items:

A Oracle REP-20147 error appears:

Cannot implement column link for this detail SQL query. Converting to group link.

Help Message:
REP-20147: Cannot implement column link for this detail SQL query. Converting to group link Cause: Reports can only insert column to column links into supported SQL. It defaults to a group to group link in this case. Action: Manually insert the required link clause into the detail SQL query.

The problem here is in the sql query!

ORDER BY something NULLS FIRST

Try removing the NULLS FIRST and the No-Link item disappears. Now you can link these two query on an item: