Using Ingest Pipelines in Opendistro

Hi guys,

i am trying to transform my documents in opendistro elasticsearch with an ingest pipeline (i enabled the security feature and use the admin user for everything). So i created a pipeline using the REST API (PUT _ingest/pipeline/my-pipeline) and configured filebeat to use this pipeline:

output:
elasticsearch:

pipeline: my-pipeline

But when watching the documents, they are not transformed, and it seems like the pipeline is ignored.
I tested it with the elastic-oss image and it works there.
Any ideas?