Disappearing items on lists

Items on my list keep disappearing when I Isync my phone. I enter something and it’s gone on my wife’s phone. She entered something and then it’s gone on my phone. Even though we sync. I can see that this question has been asked many times before but I’ve never seen where there’s been any kind of response from the app owners. Do you guys ever answer these questions? Should I just ask for a refund? Really need some help here