time code discrepency – Iphone world clock

Myself and a friend who both own sound devices 664 were working over the phone together as we have a job coming up where the company are handing the runners iphones with a free app on called ‘digi-slate’ which runs off the Iphone clock. When we lock our tentacles to the Iphone clock (time of day) – there is over a 1 second difference between the tentacle and the Iphone clock (and digi-slate app that runs off the clock on the Iphone). Both of us have the same problem – both have the older model tentacles, both of us have very latest tentacle software which allows us to set the tentacle timecode to the Iphone time, and both of us are finding the tentacle is over 1 second behind the actual Iphone clock, and also the same over 1 second behind the digi slate app which uses the Iphone clock… Both of us are having the same issue, it seems as though the tentacles are locking to the clock over a second too slowly – we have tried it for over an hour and it is always over 1 second out on both of our mixers when we compare the tentacle time code to the time on the Iphone…. It’s odd both of us, living 30 miles apart, and working seperately are finding the same issue… Can you guys please test and see if you are getting the same – locking tentacle time code to iphone clock results in a tentacle timecode that is over 1 second behind the actual Iphone 6 clock and the same behind the digi slate app that runs off the Iphone clock… Thank you for any advice you can give.