Health Service 'grey' on management servers

Hi,

We currently have an issue with a SCOM 2012 installation where the health service on both of the two Management Servers becomes 'grey'/not monitored.

Looking at the Operations Manager log on the MS, it gives the following error:

Event ID: 11904

The Microsoft Operations Manager Expression Filter Module failed to query the delivered item, item was dropped.

Property Expression: Reachability/State

Error: 0xC00CEE2C

One or more workflows were affected by this. 

Workflow name: Microsoft.SystemCenter.ManagementServicePoolWatcher.Heartbeat.Error

Instance name: All Management Servers Resource Pool

Instance ID: {BCB643D0-62C8-7555-FFE0-36C1A86101A4}

Management group:

We have tried the following:

1. Flush healt service on both MS
2. Upgrade SCOM 2012 with SP1 and UR1.
3. Remove all customizations, overrides, etc.

But the healt service is still not OK and the event ID 11904 keeps poping up…

Any suggestions would be much appreciated.

Best Regards,

GeirO