Trying to work this out while you are off for the weekend, it should be noted that the code generated for the masterKeyValue variable does NOT have the isset check generated automatically.
Code should be:
$WA_masterKeyValue = "".((isset($_SESSION["WADA_Insert_contracts"]))?$_SESSION["WADA_Insert_contracts"]:"") ."";
$WA_masterKeyValue = "".$_SESSION['WADA_Insert_contracts'] ."";
Has this issue been logged for an update? This occurs every time and is very irritating as my testing server is set to scream at me for this type of issue (unset variables!)