It used to be that when a task was mentioned inside a doc, a backlink reference (https://help.clickup.com/hc/en-us/articles/6309152582935-Create-and-view-Reference-Relationships) was created in the task back to the document.
This enabled a primary workflow where you could create tasks from documents (RMB -> Create Task) and the task would have a backreference to the document which we use to create tasks from meetings.
It seems this is now broken.
Having contacted support, they acknowledge this used to work, but this is now accepted behavior and the linked official document has been silently updated.
I follow the clickupdates, and have seen no mention of this feature being removed.