Adding customized "Parent link" fields hides child issues from the "Child issues" view in Epic parents

Issue Summary

When configuring new issue type hierarchy levels above Epic using Advanced Roadmaps, the Epics are listed under the "Child issues" panel in the issue view of the issue type you've set above Epic.

If you create customized "Parent link" fields and use them in Jira, the child issues are hidden child issues from the "Child issues" view.

Steps to Reproduce

1. Create a customized Parent link (name: Atlassian-parent-test) 
2. Associated the field with  a project's screen
3. Set both two-parent link fields in an issue of the project related to step #2. 
4. Now you could see all the child issues of parent issue in the view
5. Move the "Atlassian-parent-test" into the trash 

Expected Results

You can see the issues under the "Child issues" panel

Actual Results

In the parent issue, you can't see the child issue anymore

Workaround as of 14/Apr/2022

Delete the duplicate (non locked) Parent Link typed fields, as these fields all refer to the same value, and updating one Parent Link type field will update the value of other Parent Link type fields. Users may have multiple Parent Link type fields as Jira previously allowed users to create custom fields of this type, but no longer allows this.

Workaround prior to 14/Apr/2022

" change issue types " :

1. Check the issue that not shown in the "child issues" pannel
2. If it has been upgraded from standard-issue type, ie task , bug,story to other higher-level like epic then try to downgrade first and then upgrade  issue type again 
3.  The downgrade/upgrade will cause the original issue links missed. But you could relink that via viewing the issue history