Possible bug with `UpdateAsync` in version 1.8.0?

[DustinReagan]

Using the gitlab REST api, I am able to successfully update the default_branch of a project:

 curl --request PUT --header "PRIVATE-TOKEN: <SNIP>" --url 'https://gtlb.legacybank.com/api/v4/projects/43' --data "default_branch=dev/master"

response:

{
   "id":43,
   "description":null,
   "name":"LEAF",
   "name_with_namespace":"Digital Banking / LEAF / LEAF",
   "path":"LEAF",
   "path_with_namespace":"digital-banking/leaf/LEAF",
   "created_at":"2022-01-05T21:15:23.670Z",
   "default_branch":"dev/master",
...
}

Using GitLabAPiClient, I'm attempting to set the DefaultBranch of a Project using:

     var client = new GitLabClient("https://gtlb.legacybank.com", accessToken);
      try
      {
          var project = await client.Projects.GetAsync(projectId);  // projectId == 43
          var projectUpdate = await client.Projects.UpdateAsync(project.Id, new UpdateProjectRequest(project.Name)
          {
              DefaultBranch = branchName, // branchname == dev/master
          });
      }
      catch (GitLabException e)
      {
          var errorMsg = $"Unable to set default branch [{branchName}] at {projectId}: {e.Message}";
          Console.Error.WriteLine(errorMsg);
          return 1;
      }

Response:

GitLabApiClient.GitLabException: {"message":"403 Forbidden"}
   at GitLabApiClient.Internal.Http.GitLabApiRequestor.EnsureSuccessStatusCode(HttpResponseMessage responseMessage)
   at GitLabApiClient.Internal.Http.GitLabApiRequestor.Put[T](String url, Object data)
   at GitLabApiClient.ProjectsClient.UpdateAsync(ProjectId projectId, UpdateProjectRequest request)
   at CommandLineTools.SetDefaultBranchCommand.CommandHandler(String branchName, String projectId) in /Users/dustinreagan/code/legacy/LEAF/tools/CommandLineTools/Commands/Gitlab/SetDefaultBranchCommand.cs:line 43

In both cases, I'm using the same Gitlab Access Token and other parameters.

Any ideas?