PI Alert Rule Configuration

Hello,

I am using PI 7.3. I have got one alert as mentioned below:

"ErrText": "Conversion of file content to XML failed at position 0: java.lang.Exception:Conversion of file content to XML failed at position 0: java.lang.Exception: ERROR converting document line no. 4302 according to structure 'Detail':java.lang.Exception: Consistency error: field(s) missing - specify 'lastFieldsOptional' parameter to allow this",

If I check in Message monitor using the messsage ID which I got from the alert message, I can see that the message has already been delivered.

Please suggest what is the reason behind this alert generation?

Thanks & Regards,

Moumita