All the epic links disappeared from the tickets automatically after many times trying to re-attach

[QuynhTD (Quinn)]

We attached the epic link on the tickets successfully. And on the next day or just after that for a while, all the epic links disappeared from all the tickets automatically. We checked the logs but no one deleted them. We tried to re-attach the epic link to the tickets 2 times and they were gone again. Please check this issue for us. It doesn't happen with other projects.
Note: All the epics are still existing. And I checked the permission and project automation and they are all like other projects that I work on.
Thanks.

[Trudy Claspill]

Hello @QuynhTD (Quinn) 

Welcome to the Atlassian community.

Are you working with Jira Cloud or Jira Server/Data Center? If your URL is similar to the following you are using Jira Cloud.

https://yourCompany atlassian.net

What steps are you going through when you attach the Epic Link to an issue? Can you show us an example of an issue with an attached Epic Link? Can you show us an example of an issue where the Epic Link has disappeared?

What entries are in the History for such an issue during the time period between when you attach it and it disappears?

Does this happen for all issue types in the affected project?

[QuynhTD (Quinn)]

The URL is: https://jira.mycompany

The steps to attach the Epic Link: button "Create" -> Add information in the popup "Create Issue" including "Epic Link" like the photo below

A ticket with the attached epic link:

A ticket that the epic link disappeared:

There is no history for this issue between the 2 stages.

Currently, we use only "Story" as the issue type of ticket. We haven't tried other types.

At the same time, I'm asking other people in my company to check the configuration of Jira in my company.

[Trudy Claspill]

Hello @QuynhTD (Quinn) 

Are you still experiencing this problem?

Is the Epic Link being cleared from all issues or just some issues?

What version of the Jira product are you using? Is it Jira Server or Jira Data Center?