Case Manager is not shown for closed cases.
When closing a case, all case roles (relationships) are given an end date. This keeps them from cluttering up core screens (e.g. contact summary activity tab) where only active relationships should be shown. However it causes undesired behavior when viewing closed cases: all the case roles are gone.
One proposed solution is to show all disabled relationships when viewing a closed case. However this isn't quite right as it is then impossible to distinguish current roles from roles that ended before the case was closed.
- Stop ending/disabling relationships when a case is closed.
- Update core screens to filter out relationships from closed cases when displaying active relationships (e.g. contact summary activity tab)
- Add upgrade script to reactivate & remove end date from all activities that ended on the same date their case was closed.
Past discussions of this at https://civicrm.stackexchange.com/questions/27215/case-roles-on-closed-cases