Google Cloud Speech-to-text module not working

Trying to run a scenario using Google Cloud Speech but I get a strange error: 400 Invalid value at ‘audio’ (oneof), oneof field ‘audio_source’ is already set. Cannot set ‘content’ and I’m not able to figure out how to solve it.

The audio file is stored in Google Cloud Storage as it should be according to the documentation but still, this error appears.