App isn't syncing

Hi

Me and my partner use this app to keep track of our daughter. A few times it's taken about half an hour to sync up which hasn't really been a big problem, but We've noticed that it isn't syncing up at all now. Nothing I log is appearing on his phone, and nothing he logs is on mine - for example my phone says she only has 2 diaper changes yesterday and his says she's not fed/slept at all yesterday. It's not that bad when it comes to feeding because I always log it (EBF) but it's particularly annoying because our daughter uses cloth diapers so we like to be on a strict schedule so she doesn't leak, but seeing as we both change diapers it's harder to work out without looking at the others phone.