Amplify Push Fail - Appsync API error - S3 The specified key does not exist

I am facing an error with cloudformation in which my nested stack got stuck in UPDATE_ROLLBACK_FAILED state causing my parent stack to failed. The reason I found out is S3 key missing for my appsync resolvers, although these files are there in S3 deployment bucket. The specified key does not exist. (Service: Amazon S3; Status Code: 404; Error Code: NoSuchKey; Request ID: M2X7368PMNF1G; S3 Extended Request ID: WCIc1YLjxOR9KZRxkPb1AGI4xoM6KPofiohiP9ywyps8tSfP6ehHJl8gWk7o=; Proxy: null)