MultiTerm REST Search paging - FROM parameter does not seem to work

I am trying to implement a paged termbase search. However, regardless of the FROM value set, the result is always the same. E.g. when I try to start the page from e.g. concept ID 15, I get the same result as if I was not using any FROM parameter value at all.

            string serverUri = "servername";

            string userName = "username";

            string password = "password";

            var token = await GroupShareClient.GetRequestToken(userName, password, new Uri(serverUri), GroupShareClient.AllScopes);

            var groupShareClient = await GroupShareClient.AuthenticateClient(token, userName, password, new Uri(serverUri), GroupShareClient.AllScopes);

            SearchTermRequest _searchRequest = new SearchTermRequest("sample_termbase", "English", "*", "German", "10", "15", "test_filter"); // FROM value and page size set here

            var gsSearch = await groupShareClient.Terminology.SearchTerm(_searchRequest);

            string resultList = String.Empty;

            foreach (var term in gsSearch.Terms)

                resultList += "* " + term.TermText + "\n";

            MessageBox.Show(resultList);  // result is always the same regardless of the FROM position