TrickyRaccoon92 , after looking in the documentation a bit more it seems I am a bit wrong.

If you look here: https://clear.ml/docs/latest/docs/references/sdk/task/#upload_artifact

there is a parameter called wait_on_upload which is set by default to false. If you set it to 'True' then you should get the artifact object as well. This is due to the artifacts upload being asynchronous and I'm guessing the artifact didn't finish uploading by the time you called it.