Whenever a team-managed project issue that has an Epic (Parent) is updated through CSV import, Epic (Parent) data is wiped out

Issue Summary

Whenever a team-managed project issue that has an Epic (Parent) is updated through CSV import, Epic (Parent) data is removed even though CSV mapping does not contain any field containing Epic information.

Steps to Reproduce

1. Create a CSV to update any issue field. For example, a CSV which contains Summary, Description and Issue Key in order to update Description issue field
2. Choose for this one team-managed project issue which has an Epic as Parent
3. Import CSV data through External System Import in https://site.atlassian.net/secure/admin/ExternalImport1.jspa
4. The Description field will be updated as expected, but Epic data will be completely gone

Expected Results

Epic data should not be changed. Actually, for team-managed projects, Epic Link data importing is not even supported: https://jira.atlassian.com/browse/JSWCLOUD-17758

Actual Results

Epic (Parent) data is completely removed from the issue.

Workaround

There's a workaround using Automation for Jira to address the bug. Here is an overview of the solution, The rule is triggered when the parent field is changed, then the rule checks if the issue key is one of the issues in the CSV import. If the condition is met, the rule will update the parent again with the old value.

To use this workaround, enable the rule before the import. Once all issues are imported and their parents are updated by the automation rule, Then, the rule can be disabled so it won't affect normal changes to the parent field on these issues.

Here's a screenshot showing the rule workflow:

And here's a quick demo video showing the import of one issue on a team-managed project where the parent field was wiped out by the CSV import, but then it was restored by the automation rule: