=TODAY(), now(), etc., no longer work in forms

Just recently, I will assume, since a recent microsoft update, some basic functions of Excel no longer work. I am only assuming that is the cause since I have opened an old form created last year and it gives me the date and time the form was last updated instead of the current time and date. Can anyone suggest a work around or is there a new formula that I should be aware of? any help would be greatly appreciated.
thanks