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