I currently have Quickbooks Premier Professional Services Edition 2018 installed. I was previously able to create new To Do tasks, but this feature no longer works. When I attempt to save a new To Do task, an error dialog displays on screen (see attached screenshot).

I updated to the latest version of Quickbooks, but that did not fix the problem. I also tried populating the various fields on the entry form in different ways, but the same error always displayed when I tried to save the new To Do task.