"Create test execution" from Test Plan throws an error that the assignee automatically set by Xray is not a valid user

This happens when using the default Jira dialog for issue creation. Xray is setting the user using the user key. Although, the picker only works well with the user name.

This was working properly until the release of Jira 8.4.x where the user key was changed to be compliant with the GDPR.

References:

• https://confluence.atlassian.com/jiracore/gdpr-changes-in-jira-975041009.html#GDPRchangesinJira-userkeys
• https://jira.atlassian.com/browse/JRASERVER-69842