I think..you need to review how many activities are started before project start date.
If its very few, divide the activity and the part which is completed before project start date is add as expense line.
If number of activities are more started before project start date then change project start date. You can incorporated loss time as non working days.
Thanks for your reply. I was considering that, but needed a push to do so. I will try that.
Changing the project start date fixed the problem. All actuals are now able to spread the length of the activity now the project start date is before the activity start date.
you will need to remove the corrupted activity and add it back in and re-baseline.