User names are not showing and permissions are revoking in Jira clustering nodes

[Surender Kannemoni]

HI All

We are using Jira DC 8.20.8 with 02 nodes. In any of the node sometimes users will not syncing completely, in the place of assignee and reporter names we can see only their employee IDs, their permission are revoked completely. If any user tries to assgn users it show the error as "user not found". Please let me know what and where could be the issue?