Different asset types will use different tables. TblNetwork only stores network information for Windows computers, for Linux machines this is stored in tblLinuxNetworkDetection. We added a modified report but do note that you will get multiple rows for non-Windows devices if they have multiple network cards and IP Addresses.
Select Distinct Top 1000000 tblAssets.AssetID,
  tblAssets.AssetName,
  tblAssets.Domain,
  tsysAssetTypes.AssetTypename,
  tsysAssetTypes.AssetTypeIcon10 As icon,
  Coalesce(tblNetwork.IPAddress, tblLinuxNetworkDetection.Ipv4,
  tblMacNetwork.Ipv4, tblAssets.IPAddress) As [All IPAddress'],
  tblAssets.Lastseen,
  tblAssets.Lasttried
From tblAssets
  Inner Join tblAssetCustom On tblAssets.AssetID = tblAssetCustom.AssetID
  Inner Join tsysAssetTypes On tsysAssetTypes.AssetType = tblAssets.Assettype
  Left Join tblNetwork On tblAssets.AssetID = tblNetwork.AssetID
  Left Join tblLinuxNetworkDetection On tblAssets.AssetID =
    tblLinuxNetworkDetection.AssetID
  Left Join tblMacNetwork On tblAssets.AssetID = tblMacNetwork.AssetID
Where Coalesce(tblNetwork.IPAddress, tblLinuxNetworkDetection.Ipv4) != '' And
  Coalesce(tblNetwork.IPAddress, tblLinuxNetworkDetection.Ipv4,
  tblMacNetwork.Ipv4, tblAssets.IPAddress) Is Not Null And
  tblAssetCustom.State = 1
Order By tblAssets.Domain,
  tblAssets.AssetName