Summary

When executing a JQL search which returns the Parent Link column, issues which have Issue Links of type 'parent of' are returning empty results for the Parent Link column.  However the linked issue with the type 'parent of' will show under the Issue Links column of the search results (if shown). 

Environment

Any Jira environment with Advanced Roadmaps

Cause

Issue Links and Parent Links are not the same functionality.  Linking an issue as 'parent of' or 'child of' creates an Issue Link which is just a hyperlink that connects the issues.  The 'parent of' or 'child of' selection serves to provide metadata about that link, but does not change the issue relationship.  The Parent Link column is used to display the Parent Link custom field which is added by Advanced Roadmaps for Jira in order to establish the customizable issue hierarchy.

Solution

In order for a child issue to have its Parent Link field populated, the issue would need to have its parent link custom field set to the value of the parent issue.  This can be accomplished within the Edit Issue screen (if the parent link field is added to the screen) or within an Advanced Roadmap plan by dragging the child issue under its parent issue.  

This requires the Advanced Roadmaps hierarchy to be configured so that the child issue type is under the parent issue type in the hierarchy.  Please see the Advanced Roadmaps Guide for additional information related to issue hierarchy.