18.0.2 build 131439 GW and Mobility 18.0.1 build 280

I have a user that is complaining that appointments have to be accepted on desktop, and the mobile device. I have a Pixel, and an iPhone. The iPhone doesn't need appointment to be accepted on the device. The Android device, using the google calendar, won't accept no matter what I do to it. Removed account and reinstalled, same. The user in question has a samsung phone. Do all devices act differently?