After migrating from Classic to Next-Gen it's not possible to bulk edit epic links

Issue Summary

After migrating a Scrum project from Classic to Next-Gen I cannot bulk update epic links: in the bulk update screen I get 3 entries for the epic link field and none of them shows anything but a "no matches" in the drop-down menu:

Everything works fine when editing an issue at the time instead:

Steps to Reproduce

1. Migrate a Scrum project from classic to next-gen by following the steps in: Migrate between next-gen and classic projects
2. Run a search, select some issues, click on the 3 dots on the upper right corner and select "bulk change all xxx issues", choose "edit issues". (full instructions in: Editing multiple issues at the same time)
3. Scroll down to "Change Epic Link"

Expected Results

There is one entry to change the Epic link and in there you can select the desired Epic from the drop-down menu

Actual Results

There are multiple entries to change the Epic link and in the drop-down menu there a "No Matches" is displayed

Workaround

If you want to edit the Epic link for open issues you can use multi-select on the board or the backlog to bulk assign Stories to Epics;

If you want to update issues that are already in "Done" status instead, you can then use the below workaround. However please keep in mind that it is using an internal endpoint not officially documented/supported and this workaround might stop working without prior notice:

Send a POST request to the REST API endpoint https://INSTANCE.atlassian.net/rest/internal/simplified/1.0/projects/PROJECT-ID/issues/EPIC-ID/children providing a list of issue-ids in the request body.

Example:

• IDs of the issues to be updated: 10405, 10203
• Project ID: 10303
• Epic ID: 10519
• Curl command to set the Epic (10519) as a parent to the desired issues (10405 ,10203). Please replace all the things in CAPITAL with the proper values:

  curl -D- -u EMAIL:API_TOKEN -H "Accept: application/json" -H "Content-Type: application/json" -d '{ "issueIds" : ["ISSUE-ID-1", "ISSUE-ID-2"] }' -X POST https://INSTANCE.atlassian.net/rest/internal/simplified/1.0/projects/PROJECT-ID/issues/EPIC-ID/children
  

In order to get the list of issue-id to update you can:

1. Run a search to get the list of issues to update
2. Switch to the list view
3. Select to display only the issue-key column and export to CSV current columns only. This way you get a CSV file that only contains issue-key and issue-id. You can parse this file in many different ways to just get a coma separated list of issue-ids surrounded by double quotes

For details on how to authenticate REST API calls using API TOKENS please refer to the API tokens documentation page.