Why do my tasks jump to 'tomorrow' as soon as it is 'today' (!)

This is hard to describe in few words, hence the abstract subject line…

I have a project in Omniplan which makes use of resources (me, generally) and i use custom work hours and calendars to plan the project and see when I will need to be doing each parts.

I generally look in the evening to see what is mapped out for tomorrow and I see all the work items fit nicely, automatically, into the slots for when I am able to do them. It’s very clever. :-)

However, the next day when I come to use omniplan, and particularly when making changes (eg marking something as 100% done), all the tasks that are automatically scheduled today immediately jump to tomorrow. It seems Omniplan will never automatically schedule tasks for today. I can manually move the ‘next’ scheduled task back to today and it moves without complaint (ie there are no violations listed), but as soon as I set this task to automatically schedule, it jumps back to tomorrow. I cannot work out why it is doing this. Omniplan prefers to keep today clear. Incidentally, when I move this next task to ‘today/now’ manually, all subsequent tasks follow and schedule themselves into today.

is there a reason why it would be behaving like this? I often notice it most at weekends, but i think it does it on any day.

Thanks for the help