AIR 24 File.requestPermission throws error #1069 on Android 6.0.1

We're attempting to use the new permissions functions in AIR 24 to access files on "external" storage on Android. However, when we call requestPermission() on a File object, it throws error #1069 (property not found). We're using AIR 24.0.0.181 (a custom build provided by Adobe for a specific fix that didn't make it in time for the AIR 24 release). Any clues on what's wrong here?

Example code:

function downloadInfo(obbDir:File, infoURL:String) : void {

     var infoFile:File = obbDir.resolvePath(fileName);

     if (File.permissionStatus == PermissionStatus.GRANTED) {

          beginInfoDownload(infoFile, infoURL);

     } else {

          // need to ask for filesystem permissions

          infoFile.addEventListener(PermissionEvent.PERMISSION_STATUS, function(e:PermissionEvent):void {

               if (e.status == PermissionStatus.GRANTED) {

                    beginInfoDownload(infoFile, infoURL);

               } else {

                    // permission denied

                    trace("Filesystem permission denied by user");

                    setTimeout(function():void {

                         dispatchEvent(new Event(PERMISSION_REFUSED));

                    }, 1);

               }

          });

          try {

               infoFile.requestPermission();

          } catch(e:Error) {

               trace("Error requesting file permissions: " + e.message);

               setTimeout(function():void {

                    dispatchEvent(new Event(PERMISSION_REFUSED)); // for now, treat like it was refused

               }, 1);

          }

     }

}