Lists disappeared on iPhone still on mac and ipad

[GoodTask]

Hi @Ian_Graham, thanks for using GoodTask.

First, check on default Reminders app to see if data is properly shown on your iPhone.

If you have upgraded database on iOS 13, data may go away for a moment while it's on upgrade process. If you did and have macOS 10.14, it won't sync with upgraded iOS 13 Reminders database.

You may check details on below post.

Things to know about iOS 13 and macOS Catalina

Now the beta season is close to an end and the new OS's will start shipping from September 19th. Current release schedule that Apple announced is below. iOS 13 : September 19th iOS 13.1 & iPadOS : September 24th macOS Catalina : October There are things that you need to be cautious about with the new OS update. Data will not sync between devices using upgraded database and the ones before When you update any of your device to the new OS and open Reminders app, it'll ask you if you will upgr…

Thanks.