The custom field displays a user ID or text instead of the user object.
 Problem
The user field synchronizes, but instead of displaying the username or the user profile hyperlink, only the user ID is visible in the custom field.
 Solution
This error happens when the custom field used to map users is not a user-type custom field but a text-type custom field.
For example, when synchronizing from Jira to ADO, mapping the Reported system Jira field to an ADO text custom field, the result will be something like this:
< a href='mailto:your.user@sample.com'>your.user@sam...
For example, when synchronizing from ADO to Jira, mapping the Created By system ADO field to an Jira text custom field, the result will be something like this:
63e3b5400015d0b19c240fd1
To solve this, please use a user-type field when mapping users in both instances. Then, go to the User Mapping section in TFS4JIRA to ensure the mapping configuration is set.
Another recommendation would be to map the ‘Reporter’ Jira system field directly to the 'Created By' ADO system field.
This error can occur in TFS4JIRA Self-Hosted and TFS4JIRA Cloud Native.