Solution:
1. Upgrade to Stat 6.0 HF-x
or
2. Apply an untested one-off patch, not an official hotfix on top of Stat 5.8.0
To apply the hotfix:
1. Download from here the one-off patch stat_ora.par and rename it to stat_ora.jar.
2. Back up your stat_ora.jar file in your STAT_HOME/lib/dell and copy this over it.
3. Restart the OA and let me know if it fixed the issue.