Unable to fetch Child Issues when multiple Parent Link custom fields are in use

Issue Summary

When there are multiple custom "Parent Link" fields are used, child issues are not displayed on the issue view screen as well as for the JQL results.

Notes :

• From the plan or from Jira, create "epic" and link with parent "Initiative" then, on child epic it is showing the correct parent link however on the parent issue it is not showing the child issues
• From the plan, issues are showing properly(Parent and Child link)
• JQL “issuekey in childIssuesOf(“<parent-issue-key>“) doesn’t return a value(so, this is not a UI rendering issue)
• JQL “issuekey in parentIssuesOf(“<child-issue-key>“) is returning the correct parent ticket
• JQL "Parent Link" = "<parent-issue-key>" - No results for this JQL

Steps to Reproduce

Create multiple custom fields type of Parent Link 

Expected Results

Child issues to be seen on the Parent Issue

Actual Results

Child issues are missing on the Parent Issue

Workaround

• Rename all other Parent Link type custom fields so they're alphabetically after the original "Parent Link" (in this specific scope only the first is used).

or, ideally:

• Remove all custom Parent Link type fields, leaving only the locked Advanced Roadmaps field. In more recent versions of Jira it's no longer possible to create custom Parent Link fields.