You may have noticed after deploying patch 4 and any of the hotfixes: Hotfixes 223649, 226544, 229632 and 231411, that the MMC Notification preview keeps throwing the error:
“Value does not fall within the expected range error”
This is a product defect (TF00747451).
This is scheduled to be fixed in the Maintenance Release Patch 5 for Active Roles 6.9. ETA tentatively April/May 2018.