Not authorized when creating a ticket within a group via JSON API

Uhm, while I’m able to inspect the user with the very same token via api/v1/users/<id>, I’m not able to see the access token:

% curl --header "Content-Type: application/json" \
     --header "Authorization: Token token=abcdef" \
  --request GET \
 http://localhost:8080/api/v1/user_access_token 
{"error":"Not authorized (token)!","error_human":"Not authorized (token)!"}

Am I invoking this badly or does it reveals the problem?