loadTasks() throws FlutterDownloader.initialize() must be called first error (Android)

I'm working on getting an app upadted to new plugin and Flutter

After calling `FlutterDownloader.initialize();`
and 'FlutterDownloader.registerCallback(downloadCallback)'
and `FlutterDownloader.enqueue()`
The callback method is triggered as the download updates and calls the method `await FlutterDownloader.loadTasks();`

this produces the error;
`E/flutter (27364): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: 'package:flutter_downloader/src/downloader.dart': Failed assertion: line 111 pos 12: '_initialized': FlutterDownloader.initialize() must be called first
E/flutter (27364): #0 _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:42:39)
E/flutter (27364): #1 _AssertionError._throwNew (dart:core-patch/errors_patch.dart:38:5)
E/flutter (27364): #2 FlutterDownloader.loadTasks (package:flutter_downloader/src/downloader.dart:111:12)
E/flutter (27364): #3 DownloadManager.downloadCallback (package:nzamd/download/download_manager.dart:43:56)
E/flutter (27364): #4 callbackDispatcher. (package:flutter_downloader/src/callback_dispatcher.dart:24:13)
E/flutter (27364): #5 MethodChannel._handleAsMethodCall (package:flutter/src/services/platform_channel.dart:409:55)
E/flutter (27364): #6 MethodChannel.setMethodCallHandler. (package:flutter/src/services/platform_channel.dart:377:54)
E/flutter (27364): #7 _DefaultBinaryMessenger.handlePlatformMessage (package:flutter/src/services/binding.dart:200:33)
E/flutter (27364): #8 _invoke3. (dart:ui/hooks.dart:304:15)
E/flutter (27364): #9 _rootRun (dart:async/zone.dart:1126:13)
E/flutter (27364): #10 _CustomZone.run (dart:async/zone.dart:1023:19)
E/flutter (27364): #11 _CustomZone.runGuarded (dart:async/zone.dart:925:7)
E/flutter (27364): #12 _invoke3 (dart:ui/hooks.dart:303:10)
E/flutter (27364): #13 _dispatchPlatformMessage (dart:ui/hooks.dart:163:5)`

This is the plugin version; 1.4.1
Flutter version; v1.15.4-pre.113