[BUG] Opensearch 2.6.0 ShardBulkDocs Metrics is always empty

What is the bug?
ShardBulkDocs Metrics is always empty when calling performance Analyzer API. Other metrics are working.
I re-open the problem is still in 2.6.0 https://github.com/opensearch-project/performance-analyzer/issues/77

How can one reproduce the bug?
Steps to reproduce the behavior:

docker compose enclosed
docker-compose.txt

Follow step to activate performance analyzer : https://opensearch.org/docs/latest/opensearch/install/docker/#optional-set-up-performance-analyzer

Create test index and POST documents in this index PUT test (see enclosed)
postdata.txt

while pushing documents, call from your browser : http://localhost:9600/_plugins/_performanceanalyzer/metrics?metrics=ShardBulkDocs,ShardEvents&agg=sum,sum
you 'll get only ShardEvents numbers and no data on ShardBulkDocs

{"CkXsbxtMTDisNx2ahHqrIw": {"timestamp": 1635425175000, "data": {"fields":[{"name":"ShardBulkDocs","type":"DOUBLE"},{"name":"ShardEvents","type":"DOUBLE"}],"records":[[0.0,27.0]]}}}

What is the expected behavior?
On previous Open Distro 1.13.1 this call was working

What is your host/environment?

Opensearch 2.6.0 Docker