Youtube API: Search endpoint with videoCaption not working

The following command works as expected:

GET https://youtube.googleapis.com/youtube/v3/search?maxResults=1&q=test&key=[YOUR_API_KEY] HTTP/1.1Authorization: Bearer [YOUR_ACCESS_TOKEN]Accept: application/json

The following does not work as expected:

GET https://youtube.googleapis.com/youtube/v3/search?part=snippet&maxResults=1&q=test&videoCaption=closedCaption&key=[YOUR_API_KEY] HTTP/1.1Authorization: Bearer [YOUR_ACCESS_TOKEN]Accept: application/json

This is the full error:

{"error": {"code": 400,"message": "Request contains an invalid argument.","errors": [      {"message": "Request contains an invalid argument.","domain": "global","reason": "badRequest"      }    ],"status": "INVALID_ARGUMENT"  }}

This should work according to the documentation: https://developers.google.com/youtube/v3/docs/search/list

Could someone please help?

Best,Andy