In my code I am generating false ground truth and invoke the model as follows:
def generate_load_and_ground_truth():
    df = pd.read_csv('validation_with_predictions.csv')
    gt_records = []
    for i, row in df.iterrows():
        suffix = uuid.uuid1().hex
        inference_id = f'{i}-{suffix}'
        data = np.array([X_test[i]])
        payload = {'instances': data}
        args = {'InferenceId': inference_id}
        out = predictor.predict(data = payload, initial_args = args)
        gt_records.append(str({
            "groundTruthData": {
                "data": str(df['label'][i]),
                "encoding": 'CSV',
            },
            "eventMetadata": {
                "eventId": str(inference_id),
            },
            "eventVersion": "0",
        }))
    upload_ground_truth(gt_records, ground_truth_upload_path, datetime.utcnow())
def upload_ground_truth(records, path, upload_time):
    data_to_upload = ",".join(records)
    data_to_upload = data_to_upload
    target_s3_uri = f"{path}/{upload_time:%Y/%m/%d/%H/%M%S}.jsonl"
    print(f"Uploading {len(records)} records to", target_s3_uri)
    S3Uploader.upload_string_as_file_body(data_to_upload, target_s3_uri)
When the model schedule ran it gave the error message
'MonitoringExecutionStatus': 'Failed',
'FailureReason': 'Algorithm Error: See Job Logs for more information.'
Looking into the cloud watch log I found the error to be:
'Cannot resolve column name "groundTruthMetadata.eventId" among (_corrupt_record);'
Then I used this pre-process function at my endpoint.
import json
def preprocess_handler(inference_record):
    input_dict = json.loads(inference_record.endpoint_input.data)
    output_dict = json.loads(inference_record.endpoint_output.data)
    input_data = str(input_dict['instances'].reshape(3072))[1:-1]
    output_data = str(np.argmax(output_dict['predictions'][0]))
    return_dict = {'prediction000':output_data, 'feature000':input_data}
    return return_dict
It gives the error:
 'FailureReason': 'InternalServerError: We encountered an internal error.  Please try again.'}
Sample data in inference_record is:
{
	"captureData": {
		"endpointInput": {
			"observedContentType": "application/json",
			"mode": "INPUT",
			"data": data, 
#"{'instances': [[[[0.6196078658103943, 0.43921568989753723, 0.1921568661928177]]]]}",  
# SAMPLE OF data_lst VERSION; dict with 4 dimensional array
			"encoding": "JSON"
		},
		"endpointOutput": {
			"observedContentType": "application/json",
			"mode": "OUTPUT",
			"data": "{\n    \"predictions\": [[0.000721988094, 0.000489010592, 0.0307604838, 0.291437089, 0.0597994663, 0.462541133, 0.110468164, 0.041162733, 0.00192647439, 0.000693516282]\n    ]\n}",
			"encoding": "JSON"
		}
	},
	"eventMetadata": {
		"eventId": "eb71956e-9d99-4bfe-a35f-6d5a33c7e701",
		"inferenceId": "155-a02fa0aaf86211ec9a027f52933c247f",
		"inferenceTime": "2022-06-30T10:51:41Z"
	},
	"eventVersion": "0"
}
