I have this problem too. This is the exact error that I get when I try to save a task:
Please save the task order by clicking save task order on the actions menu in the "tasks" folder. The view must not be filtered or grouped for save task order to be available. Could not complete operation. one or more parameter values are not valid.
Mind you, I do not use the add-in. I bought the Outlook configuration pdf and configured my outlook per the instructions. What's happening is when my tasks are grouped by category with completed tasks filtered out, which is the recommended fashion for using Outlook to work within the GTD processes, I cannot save a new task.
I need to be able to save a new task when my tasks are grouped by category with completed tasks filtered out just like everyone else. Thanks. BTW, other than this the outlook configuration pdf is really great and I recommend it for anyone that's willing to go about doing the configuration work themself. Lots of tips and shortcuts that would take for working in outlook that would take me a bundle time to figure out on my own, if ever.
Anyhow, anyone ever have and resolve this task saving issue?