Changing Start Date - Why can't you do it?
 

I have a project plan with a task where:

- there are no prerequisites or dependencies
- it is after the start date of the project
- the assignee does not have enough tasks assigned to them to push out this task in question as much as it is

I'm assuming the software is making any insane assumptions that I have no visibility into. What is stopping me from changing this? How can I adjust start time. Removing the constraint does not seem to help, and the start date keeps going back to the date I changed it from!

Difficult to say without seeing the document. I suggest you use the Help->Send Feedback command in OmniPlan to send a copy of your document to the Omni support folks. It converts all of the task names and so on back to generic things like Task 1, Task 2, Resource 1, etc. and overwrites the notes, so no sensitive information is sent. You can verify this by looking in the file before sending.

Because the identifying information is scrubbed away, you'll need to give them a WBS number (just to the left of the task name, 1.3.6 for example) to tell them which task it is that is giving you trouble.