Problems compiling NAV 2018 Outlook Synch. Codeunits

I am getting various compile errors trying to compile my NAV2018 Demo database. Specifically Outlook Sync. Codeunits 5304..5310; they all comeback to this error:

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Microsoft Dynamics NAV Development Environment
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Could not load type 'Microsoft.Dynamics.NAV.OLSync.Common.XmlTextWriter.'Microsoft.Dynamics.Nav.OLSync.Common, Version=11.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35''.
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OK
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I have installed the Outlook Sync components (and uninstalled everything and reinstalled) and I get the same errors. Any thoughts?