Parameter Validation Failure : Salesforce Query Component : The component was unable to read job variables even if default values has been set

I have a parent and child jobs , The standalone child job has Salesforce Query components . I have parameterized all the inputs such as Database, Schema and Table etc..The job was runinng fine until today . The standalone child job validates successfully ,but when I validate the parent job that references the child job, it does not validate as it says thechild job has errors. I have attached the screenshot. I observed that it's not able to recognize the default values set in the job variables of child jobs. SO I modified all my parameters to take a default value and it worked. But this is weird and inefficient way to handle.It looks cumbersome as well as.

 

${jv_warehouse ? jv_warehouse:'MATILLION_WH'}