Why such a delay in the sync function of iCal ?

I am running a MacBookPro and iPhone5S. I have been successfully using iCloud and iCal for several years now across numerous iPhones and just in the last 3 days, I can load an appointment into my MBP and several hours later it still does not appear on the iPhone calendar.

I have tried resetting the devices. I have turned iCloud off and on, on both devices separately and simultaneously, nothing is getting me back to instantaneous syncing. I used to be able to load my MBP and then watch my iPhone make the identical update sitting alongside me. This is incredibly frustrating right now. Especially when I load data into a calendar event to take to a meeting and then its not there when I have walked 30 minutes to the appointment.

Anyone have some advice ?