Error while requesting a transaction with CXAnswerCallAction when the app is in background

I have an auto answer functionality in my app. When I get an incoming call and the app is in background, the CallKit screen is shown, after the auto answer interval (i.e. 5 secs) is over, I create CXAnswerCallAction with the proper call UUID and requested a transaction and I get this error:

Code Block language
Error Domain=com.apple.CallKit.error.requesttransaction Code=6 "(null)"

According to the documentation:

Code 6 is CXErrorCodeRequestTransactionErrorInvalidAction

It was working before in the previous versions of the iOS but suddenly it stops working. Is there anything we can do. Any help related to the issue is really appreciated.