"behavior.on.null.values": "delete" doesn't work properly

I'm working with opensearch-connector-for-apache-kafka-3.0.0.
The "behavior.on.null.values": "delete" doesn't work properly.
Sometime delete with success.
Othertime it doesn't delete and there are several duplicated elements in the indexes.
This is my opensearch sink configuration:

{
"name": "open-sink-yyy-user-profiling-xxx",
"config": {
"connector.class": "io.aiven.kafka.connect.opensearch.OpensearchSinkConnector",
"type.name": "kafkaconnect-yyy-crsm",
"behavior.on.null.values": "delete",
"connection.password": "",
"topics": "yyy-attributes-category-xxx,yyy-business-user-profiles-xxx,yyy-user-roles-xxx,yyy-business-users-xxx,yyy-offering-business-users-xxx,yyy-users-xxx,yyy-offering-users-xxx,yyy-user-attributes-xxx,yyy-user-relationships-xxx,yyy-user-invitations-xxx,yyy-users-devices-xxx,yyy-iam-group-mappings-xxx",
"tasks.max": "10",
"batch.size": "500",
"connection.timeout.ms": "30000",
"connection.username": "",
"max.retries": "12",
"retry.backoff.ms": "1000",
"schema.ignore": "true",
"value.converter.schemas.enable": "false",
"name": "open-sink-yyy-user-profiling-xxx",
"errors.tolerance": "all",
"connection.url": "http://dcpp-opensearch-cluster:9201",
"value.converter": "org.apache.kafka.connect.json.JsonConverter",
"read.timeout.ms": "30000",
"key.converter": "org.apache.kafka.connect.storage.StringConverter",
"behavior.on.version.conflict": "warn"
},

We tried also without this setting "behavior.on.version.conflict": "warn"

But in that case the connectors fails and doesnt't work for any operation with this kind of exception

"trace": "org.apache.kafka.connect.errors.ConnectException: Exiting WorkerSinkTask due to unrecoverable exception.
at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:560)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:321)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:224)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:192)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:175)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:219)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at java.base/java.lang.Thread.run(Thread.java:834)
nCaused by: org.apache.kafka.connect.errors.ConnectException: Failed to bulk processing after total of 1 attempt(s)
at io.aiven.kafka.connect.opensearch.RetryUtil.callWithRetry(RetryUtil.java:137)at io.aiven.kafka.connect.opensearch.BulkProcessor$BulkTask.execute
(BulkProcessor.java:367)
at io.aiven.kafka.connect.opensearch.BulkProcessor$BulkTask.call(BulkProcessor.java:356)
at io.aiven.kafka.connect.opensearch.BulkProcessor$BulkTask.call(BulkProcessor.java:337)...
4 more\nCaused by: org.apache.kafka.connect.errors.ConnectException: One of the item in the bulk response failed. Reason:
[yyy-user-invitations-xxx/0FNsOYA_R2-Qx7JM04k6Fw][[yyy-user-invitations-xxx][0]]
OpenSearchException[OpenSearch exception [type=version_conflict_engine_exception,
reason=[yyy-1f585694-df20-4a97-bb29-0e73fb5a4832]: version conflict, current version [3] is higher or equal to the one provided [0]]]
at io.aiven.kafka.connect.opensearch.BulkProcessor$BulkTask.handleVersionConflict
(BulkProcessor.java:429)at io.aiven.kafka.connect.opensearch.BulkProcessor$BulkTask.lambda$execute$0(BulkProcessor.java:382)
at io.aiven.kafka.connect.opensearch.RetryUtil.callWithRetry(RetryUtil.java:119)... 7 more\n"

Please can you help me?
Regards
Gabriella