unfortunately, all currently available Todoist apps are third party solutions and we can't guarantee their reliability. We will release our own iPhone app soon, though.
Still, in case this is a global issue, please tell me:
- Can you add sub-tasks when accessing Todoist directly through a web browser on your computer?
- What exact action do you perform when adding a sub-task (do you indent the task after adding it)?
- Do you see an error message? If so, what does it say and what action triggers it?
- Which iPhone app are you using?
We are pleased to announce that the Todoist Mobile application for iOS is now available at the App Store: http://itunes.apple.com/us/app/todoist/id476672770?ls=1&mt=8
It can be downloaded for FREE. It's compatible with iPhone, iPod Touch and iPad (requires iOS 3.0 or later). Beside all standard Todoist's features, Todoist for iOS also includes OFFLINE SYNC.
We will soon release the Android version as well and will notify you once it's been published.
Thank you for your patience and continued support, we hope this App will increase your productivity and provide a great extension for Todoist's functionality which we will continue to develop according to your suggestions and feature requests posted in our Votebox: http://todoist.com/Vote/
If you have any questions or suggestions for the improvement of this App or experience any issues with it, please post them in this thread: http://todoist.com/Support/showQuestion/720/
We appreciate any feedback.