Mongo Golang Driver BulkWrite Write Conflict Error with No Details

We are testing the Mongo Golang Driver in our environment and we are noticing a fair amount of WriteConflicts errors on/off on BulkWrite.
—> r, err = md.dbHandle.GetCollection(key).BulkWrite(sctx, val)

These errors show up without any reason. So I am not sure what is causing this error. In this particular case, the Bulk transaction itself has just one Op.

Here is the error we receive: [(WriteConflict) Encountered error from mongo-cluster1-shard1-node1-svc:27018 during a transaction :: caused by :: WriteConflict]

Any suggestions on what we need to do to further debug this issue. This does not happen all the time.
Will an upgrade of the driver solve this issue or at least give a clue of why it is throwing this empty Write Conflict error?

We are using a 3 node replica set with Mongo version: “4.2.14”.
Our Driver Version is “v1.4.7”

I upgraded the mongo driver to 1.5.3 and still sees the same write conflict error with no reason.