Exchange MSExchange Mid-Tier Storage Audit Event 2006

Hello all

I am suddenly seeing massive amounts of a warning event in the event logs of a clients mailbox server.
I am unable to find any information about this event online so I will greatly appreciate any help I can get.

They are running  Exchange Server 2013 Cumulative Update 13 (CU13)
Event ID: 2006
Source: MSExchange Mid-Tier Storage
Task Category: Audit
Level: Warning
MSExchange Mid-Tier Storage\Audit is set to expert.


[Process:Microsoft.Exchange.RpcClientAccess.Service PID:5228 Thread:20] Error occurred while resolving message subject of item 'RgAAAABeMdWMNpvUEaksABCD/cLrBwDLOAZHh47UEaksABCD/cLrAAAADXRSAADGDdo4yer+SJrft/Gu4Qw1AAAZlGQ5AAAA'. The subject of this item will not be available. Current mailbox: 'example@example.com' a0b52fb3-85b6-412c-a6c6-4d3e123d0cae. Logon type: Owner. Logon user SID: 'S-1-5-21-72666444-1982495053-1246845465-1042'. Operation: SoftDelete. Exception details:
Microsoft.Exchange.Data.Storage.ObjectNotFoundException: The process failed to get the correct properties. ---> Microsoft.Mapi.MapiExceptionNotFound: MapiExceptionNotFound: Unable to get properties on object. (hr=0x8004010f, ec=-2147221233)
Diagnostic context:
    Lid: 55847   EMSMDBPOOL.EcPoolSessionDoRpc called [length=843]
    Lid: 43559   EMSMDBPOOL.EcPoolSessionDoRpc returned [ec=0x0][length=238][latency=0]
    Lid: 52176   ClientVersion: 15.0.1210.3
    Lid: 50032   ServerVersion: 15.0.1210.6003
    Lid: 23226   --- ROP Parse Start ---
    Lid: 27962   ROP: ropOpenMessage [3]
    Lid: 17082   ROP Error: 0x8004010F
    Lid: 26977  
    Lid: 21921   StoreEc: 0x8004010F
    Lid: 27962   ROP: ropExtendedError [250]
    Lid: 1494    ---- Remote Context Beg ----
    Lid: 50428  
    Lid: 59416   StoreEc: 0x8004010F
    Lid: 38536  
    Lid: 10786   dwParam: 0x0        Msg: 15.00.1210.000:HA-PRD-MBX01
    Lid: 1750    ---- Remote Context End ----
    Lid: 27962   ROP: ropGetPropsSpecific [7]
    Lid: 17082   ROP Error: 0x4B9    
    Lid: 26465  
    Lid: 21921   StoreEc: 0x4B9    
    Lid: 31418   --- ROP Parse Done ---
    Lid: 22753  
    Lid: 21817   ROP Failure: 0x4B9    
    Lid: 20385  
    Lid: 28577   StoreEc: 0x8004010F
    Lid: 32001  
    Lid: 29953   StoreEc: 0x8004010F
    Lid: 32768  
    Lid: 33024   StoreEc: 0x8004010F
   at Microsoft.Mapi.MapiExceptionHelper.InternalThrowIfErrorOrWarning(String message, Int32 hresult, Boolean allowWarnings, Int32 ec, DiagnosticContext diagCtx, Exception innerException)
   at Microsoft.Mapi.MapiExceptionHelper.ThrowIfError(String message, Int32 hresult, IExInterface iUnknown, Exception innerException)
   at Microsoft.Mapi.MapiProp.GetProps(ICollection`1 propTagsRequested)
   at Microsoft.Exchange.Data.Storage.MapiPropertyBag.GetProperties(IList`1 propertyDefinitions)
   --- End of inner exception stack trace ---
   at Microsoft.Exchange.Data.Storage.MapiPropertyBag.GetProperties(IList`1 propertyDefinitions)
   at Microsoft.Exchange.Data.Storage.StoreObjectPropertyBag.InternalLoad(ICollection`1 extraProperties)
   at Microsoft.Exchange.Data.Storage.StoreObjectPropertyBag..ctor(StoreSession session, MapiProp mapiProp, ICollection`1 autoloadProperties, Boolean canSaveOrDisposeMapiProp)
   at Microsoft.Exchange.Data.Storage.ItemBuilder.CoreItemBind(StoreSession session, StoreId storeId, MapiMessageCreator mapiMessageCreator, ItemBindOption itemBindOption, ICollection`1 propertiesToLoad, StoreObjectType& storeObjectType)
   at Microsoft.Exchange.Data.Storage.CoreItem.Bind(StoreSession session, StoreId storeId, ICollection`1 propsToReturn)
   at Microsoft.Exchange.Data.Storage.COWAudit.InternalGroupOperation(COWSettings settings, IDumpsterItemOperations dumpster, COWTriggerAction operation, FolderChangeOperationFlags flags, StoreSession sourceSession, StoreSession destinationSession, StoreObjectId destinationFolderId, StoreObjectId[] itemIds, GroupOperationResult result, Boolean onBeforeNotification, CallbackContext callbackContext)