Try this report to check issue with scan Windows OS version:
Select Top 1000000 tblAssets.AssetID,
  tblAssets.AssetUnique,
  tblAssets.Domain,
  tblAssets.Username,
  tblAssets.Userdomain,
  tblAssets.IPAddress,
  tblAssets.Mac,
  tsysIPLocations.IPLocation,
  tblAssets.Firstseen,
  tblAssets.Lasttried,
  tblAssets1.AssetID As deviceassetid,
  tblAssets1.AssetName As deviceassetname,
  tblSNMPAssetMac.IfIndex As SwitchPort,
  tblSNMPInfo.IfDescription As PortDescription,
  tblSNMPInfo.IfSpeed / 1000000 As ifSpeedMb,
  tblAssets.Lastseen,
  tblAssets.LastseenCredentials,
  tblAssets.LasttriedCredentials,
  tblAssets.LasttriggeredCredentials
From tblAssets
  Left Join tsysIPLocations On tsysIPLocations.LocationID = tblAssets.LocationID
  Left Join tblSNMPAssetMac On tblAssets.Mac = tblSNMPAssetMac.AssetMacAddress
  Left Join tblAssets tblAssets1 On tblAssets1.AssetID = tblSNMPAssetMac.AssetID
  Left Join tblSNMPInfo On tblAssets1.AssetID = tblSNMPInfo.AssetID And
      tblSNMPAssetMac.IfIndex = tblSNMPInfo.IfIndex
Where tblAssets.Assettype = -1 And IsNull(tblAssets.oscode, '') = ''
Order By tblAssets1.lastseen