Message Id not matched signifies that the DLR received from vendor is not matching with Message ID which was originally sent in submit_sm response.
a. Message id recieved from gateway vendor in submit_sm response is c86d461a-a349-4354-8b3a-ae5614eb0541
b. Message id recieved from gateway vendor in deliver_sm request is 5b718c13-9372-4805-9d3a-2629b983add5
In that above case the DLR message id doesnt matches with the submit_sm response message id, leading to non updation in DLR and such logs will appear under Event Viewer Logs.