Unable to create subtasks in Reminders on macOS or iPadOS

I finally upgraded to Catalina on my Mac (10.15.4) and iPadOS (13.4.1) on my Air 3. I have been really looking forward to using subtasks in Reminders; however, I cannot get them to work.

I have read other Community threads on issue, but the solutions for those do not seem to work. Actually, in some cases, the steps do not even appear to be possible for my devices.

1. Apple's instructions for both OSes state that the user will be given the option to upgrade the iCloud Reminders database on first launch. I was not presented with any such option on either OS.
2. I reviewed Apple's instructions for upgrading after the initial launch on both platforms. The instructions identify "upgrade" UI widgets that I do not see on my devices. I have tried all the menu items, all the buttons, etc. with no luck.
3. Both devices are connected to iCloud. If I add a list or a task on one device, it quickly shows up on the other.
4. On the Mac, the menu items for indenting, outdenting, and managing subtasks are disabled.
5. The Info button on both devices does not show any indication that subtasks can be managed.
6. On the iPad, I can swipe left to delete a task, but Reminders does not respond to a right swipe on a task (in order to create a subtask.
7. I cannot drag-n-drop one task onto another on the Mac to create a subtask.
8. Assuming that this situation might be influenced by the iPad we have that has not yet been updated or the two iPhones we have that are too old be updated, I turned off iCloud Reminders syncing on these three devices. No improvement.
9. And so on...

My best guess is that the Reminders data has not been upgraded; however, I could really use some instructions for upgrading the Reminders database that are different than the ones that Apple provided! Can't tap a button that doesn't exist.