OmniPlan 3.12.3, created a project today (11/08/19), and needed to log a few tasks that started last week (11/04/19), after reading the docs, I performed the following steps:
From the Project menu, select Set Current Editing Date…, and set the current date to 11/04/19;
Select a task in the Task View;
On the Task Inspector, set the start date to 11/04/19;
However, the start date didn’t get changed, only the Start No Earlier Than constraint got changed to 11/04/19.
Problem solved. I had a task group enclosing this specific task, once I changed the start date of this outer task group, the inner task start date got changed as well.
I was expecting that when pushing back the start date of a task, the enclosing group’s start date should also get pushed back accordingly, but unfortunately that wasn’t the case. Just a suggestion that this automatic push back be considered in the next release, so that the behavior is aligned with the usual forward scheduling one.