Your form is showing the Deactivation message prematurely because of the way the dates are being handled.

For example, setting a deactivation date of 5/9/2018 - which is September 5th 2018 in UK/EU date format - will cause the form to show inactive because the system perceives this date to be May 9th 2018.

We have qualified this behavior as a Bug in our software. Our current suggestion is to manually deactivate your forms when your grant deadline is reached as we troubleshoot this matter further.