I manage my do.it tasks online normally, but I also use the iphone app, however it's partly unusable because it doesn't sync properly and shows many tasks I've already checked as completed on the web version. It has always done this both on the iPad when it was available and on the iphone, I just never reported it before now.
For reference, I am no longer using the unsupported iPad App, just the newest iphone version and it's unusable because of this.