Sharepoint on prem update

I have been using Nintex Cloud and build many workflows with it. I’m trying to workout one particular workflow and update the same in sharepoint on prem and it is weird that every time the item gets created without any issue. Once it reaches the update item I get the error “Received an error response from the connector: NotFound, ResponseStatus: Completed -”; I cannot understand why it behaves so only for this workflow as I have done the same steps in all my previous workflows. I am exhausted coz i have tried to make new connections, rebuild things but everytime it throws the same error. I had raised support ticket but to no avail. Any experts who can solve this issue so that I can make some progress in it?