Unable to replicate mAP scores on object detection

[vadthyavath]

After tuning, Sagemaker reports mAP of 71% on the validation set. Then I deployed this model and made predictions on the test set. But I couldn't get mAP scores close to validation set.

So in order to validate mAP metric computation, I made predictions on the validation set and then computed mAP scores. Validation mAP score which I computed doesn't match with sagemaker reported mAP score.

Then to validate mAP scoring criteria, I have used Gluoncv code from here (https://cv.gluon.ai/_modules/gluoncv/utils/metrics/voc_detection.html) and other repo from here https://github.com/microsoft/vision-evaluation/blob/e82f087a4993b8852b8873a2d6c8ec474faa95dd/vision_evaluation/evaluators.py#L373

But I was unable to replicate sagemaker mAP scores.
Could you please provide references to the code which sagemaker uses to compute mAP score?
update: coco based mAP scores also doesn't match.