When using mongoimport tool to insert sample data (100000000 rows totally),
if chunkSize is set to 50MB, there is about 20000 rows data lost .
But when using default chunkSize (200MB) , there is No data loss.

The shard environment contains 2 Shards , 2 Shards + 2 Replicas, 4 Shards + 4 Replicas.
Once chunkSize is set to 50MB, the data must be lost.

When chunkSize is set to 50MB, the mongos log contains too many autosplit failure.such as
ERROR: splitIfShould failed: locking namespace failed
or
ERROR: saving chunks failed.

I think the autosplit process failure is normal when use small chunkSize.
But the data loss is weird.

the attachment contains all logs when using 2 shards.