Hi Susanna - I haven't had this problem with the World SS but I usually start a new one each year. If you go to the US tab on your SS, and select a cell after March 31st, is there anything showing on the function line (labeled fx, above the A, B, C column headings). Mine all show as either something like "='World mmol_L'!C97" or "=ROUND(('World mmol_L'!B99*18),0)". That way you know it's trying to get the values from the World Tab.
Not sure how to help you if it's not, other than suggest copying and pasting the formatting. You might want to post in the Tech Forum, there might be someone there who could help.
By the way, when you don't shoot, it's helpful to put something like NS (no shot) in the units column so people know you didn't shoot instead of just forgetting to enter the amount. Was today the third cycle without insulin? Great start if so.