MacOS – Missing Reminders since upgrade to Catalina beta

On the iPad Reminders app, there is no + button when viewing Completed tasks.

What happens when you click on Data? Can you then add items?

Edit

It looks like others are having the same problem. Does this reply work for you:

here's the solution that seems to work... have tried it, reversed it, and retried and it worked twice.  Turn on reminders in icloud.  go to reminder app.... + should now be there.  i then turned off reminders becasue it seems to just drain the battery... but select option to keep remdiners on the iphone when it prompts you.

After further research is seems as though Siri creates "Tasks" on my Exchange server, which don't allow geofencing. What is needed is an iCloud "Reminder", which does allow for Geofence reminders. You need to set up Reminders to use iCloud by default as follows:

• Make sure your iCloud account is setup online, and enable the same iCloud account on your iPhone.
• Make sure that the notifications and calendars are syncing with iCloud on your iPhone.

Next you will need to navigate to Settings >> Reminders:

Once these steps are completed the reminders functionality (with geofencing alerts) should work properly (even with Exchange). You will obviously need to designate Geo points via a contact entry with address information on the iPhone itself for this to work (i.e. Work, Home, etc..). There is a lot of good information on this question along with a trouble shooting process in this Apple forum thread located here. Please note that this process was tested on an iPhone 5 with iOS 6 (build 10A405) on an AT&T cellular network.