Synchronization editor: Preparing report stuck at the end

Check the synchronization editor logs to see what is happening. Do you have all of the log settings set for the target system connection and the Identity Manager connection in the synch editor? If so that will create a lot of information in the sync summary which generates a lot more detail and bigger logs. I would suggest setting the logging with less options.

You could also run the following query.

SELECT m.MessageContext
	,m.MessageString
	,m.MessageType
	,m.SequenceNumber
	,j.CreationTime
	,j.ProjectionContext
	,j.ProjectionConfigDisplay
	,j.SystemVariableSetDisplay
	,j.DisplayNameQualified
FROM DPRJournalMessage m
LEFT OUTER JOIN (
	SELECT j.UID_DPRJournal
		,j.CreationTime
		,j.ProjectionContext
		,j.ProjectionConfigDisplay
		,j.SystemVariableSetDisplay
		,c.DisplayNameQualified
	FROM DPRJournal j
	JOIN DPRProjectionConfig c ON j.UID_DPRProjectionConfig = c.UID_DPRProjectionConfig
	) AS j ON m.UID_DPRJournal = j.UID_DPRJournal
WHERE MessageType <> N'I'
ORDER BY j.CreationTime DESC

I'ts not recording all the values. The query from Niels returns cca 3000 lines.

What version of OneIM is it?

The 3000 lines are just the DPRJournalMessages (3000 are many for this type as well but not a problem for the report).

I assume you do have many rows in DPRJournalProperty.

How many rows do you get with this query?

Declare @DPRJournal as Varchar(38)
Set @DPRJournal='<Your UID_DPRJournal>'

SELECT j.CreationTime
	,j.ProjectionContext
	,j.ProjectionConfigDisplay
	,j.SystemVariableSetDisplay
	,o.ObjectDisplay
	,o.ObjectState
	,p.PropertyName
	,p.NewValueShort
FROM DPRJournal j
JOIN DPRJournalObject o on j.UID_DPRJournal = o.UID_DPRJournal
LEFT OUTER JOIN DPRJournalProperty p on o.UID_DPRJournalObject = p.UID_DPRJournalObject
WHERE j.UID_DPRJournal = @DPRJournal
Order By O.SequenceNumber