Report showing user who unmanaged elements and muted alerts

Great. So if you run the original query to show muted nodes, but you refer to EventTypes 55 and 56, does that produce the results you expected? Here's the revised query using your EventTypeIDs:

Edited 2018-05-03 to account for variation in Orion.AuditingActionTypes.ActionTypeID across installations.

Select N.Caption, Supp.SuppressFrom, Supp.SuppressUntil, LastMuteEvent.TimeLoggedUtc, AE.AccountID   
from Orion.Nodes N   
INNER JOIN Orion.AlertSuppression Supp on Supp.EntityUri = N.Uri   
LEFT OUTER JOIN (   
SELECT NetObjectID, Max(AuditEventID) as [AuditEventID], Max(TimeLoggedUtc) as [TimeLoggedUtc]   
FROM Orion.AuditingEvents   
where ActionTypeID in (  
SELECT ActionTypeID  
FROM Orion.AuditingActionTypes  
where ActionType = 'Orion.AlertSuppressionAdded'  
or ActionType = 'Orion.AlertSuppressionChanged'  
)   
group by NetObjectID   
) AS [LastMuteEvent] on LastMuteEvent.NetObjectID = N.NodeID   
LEFT OUTER JOIN Orion.AuditingEvents AE on AE.AuditEventID = LastMuteEvent.AuditEventID   
ORDER BY N.Caption  

So as an FYI, depending how old someone's instance is, and how many modules they have installed the audit events and regular events tables will have all kinds of different numbers for eventids.  To make a query work in other people's environments I find it is 100% required to write queries with a join to the relevant types tables tables and filter based on the name strings.

Who thought that was a good idea?

(Breathe)

This query will get the muted nodes regardless of what values your particular installation has for those audit event IDs:

Select N.Caption, Supp.SuppressFrom, Supp.SuppressUntil, LastMuteEvent.TimeLoggedUtc, AE.AccountID 
from Orion.Nodes N 
INNER JOIN Orion.AlertSuppression Supp on Supp.EntityUri = N.Uri 
LEFT OUTER JOIN ( 
SELECT NetObjectID, Max(AuditEventID) as [AuditEventID], Max(TimeLoggedUtc) as [TimeLoggedUtc] 
FROM Orion.AuditingEvents 
where ActionTypeID in (
SELECT ActionTypeID
FROM Orion.AuditingActionTypes
where ActionType = 'Orion.AlertSuppressionAdded'
or ActionType = 'Orion.AlertSuppressionChanged'
) 
group by NetObjectID 
) AS [LastMuteEvent] on LastMuteEvent.NetObjectID = N.NodeID 
LEFT OUTER JOIN Orion.AuditingEvents AE on AE.AuditEventID = LastMuteEvent.AuditEventID 
ORDER BY N.Caption

This query will get the unmanaged nodes regardless of what values your particular installation has for those audit event IDs:

Select N.Caption, N.UnManageFrom, N.UnManageUntil, LastUnmanageEvent.TimeLoggedUtc, AE.AccountID  
from Orion.Nodes N   
LEFT OUTER JOIN (  
SELECT NetObjectID, Max(AuditEventID) as [AuditEventID], Max(TimeLoggedUtc) as [TimeLoggedUtc]  
FROM Orion.AuditingEvents   
where ActionTypeID=
(
SELECT ActionTypeID
FROM Orion.AuditingActionTypes
where ActionType = 'Orion.NodeUnmanaged'
)   
group by NetObjectID   
) AS [LastUnmanageEvent] on LastUnmanageEvent.NetObjectID = N.NodeID  
LEFT OUTER JOIN Orion.AuditingEvents AE on AE.AuditEventID = LastUnmanageEvent.AuditEventID  
Where Unmanaged = TRUE   
ORDER BY N.Caption