Error While Import Mapping

Hi Team, I am trying to Import Data from Rest API . For Most of the Queries it works.  However, for 1 Particular Query it fails. with no proper error.  when i compare the Json’s working and non working i dont see any difference. below are error Screen shots. Let Me know in case you know the cause.  And ya one more thing i tried to import the same json on a dummy project it worked over there.. 
1 answers

Thanks for the help Arendonk and Horst,

I tried to debug more based on your suggestions : 

API is not called multiple times. 

during the process i found an alternate to fix the issue. however, i could not understand the cause of this 

In my import mapping i used to get the object from input parameter and then pass it to object. when i tried to create a new object it works. 

so alternative used is creating the object instead of using the existing one.