Greenhopper/jira session corrupts with GH 3.0.2 and Jira 3.12.3 standalone

Greenhoppers session breaks, this happens only when using greenhopper plugin, normal jira usage works fine. Jira ask often after greenhopper operation to login again. This seems to make GH fully unusable for some our GH users.

In the log there is following type of errors.

2008-09-30 10:24:41,677 http-8080-Processor15 ERROR [500ErrorPage] Exception caught in 500 page User 'null' does not have permission to see issue 'QUIT-246'
com.atlassian.jira.exception.IssuePermissionException: User 'null' does not have permission to see issue 'QUIT-246'
com.atlassian.jira.exception.IssuePermissionException: User 'null' does not have permission to see issue 'QT-119'