How it works: Backup and restore for Microsoft Authenticator

I've got a pretty basic issue with the Microsoft Authenticator - or maybe it's just the documentation/help.

To ensure I can recover from loss/theft/etc, I've turned on "Cloud backup" in the Authenticator app's settings on my android phone. The immediate question that comes to mind is whether this is a one-off backup, or whether MS Authenticator is going to keep "syncing" to the secure cloud-backup (linked to my MS account) all subsequent additions/changes/etc to the accounts I store in Authenticator. I assume it is an ongoing process because I "turn on" the cloud-backup rather than just "creating" it. But this is not confirmed in any MS documentation I have found - apart from one article in the Azure Active Directory Blog, which states:

"Once you turn cloud backup on, your data is encrypted and stored with your personal Microsoft account. Your account credentials stay updated when you add, delete, or edit your accounts."

However, if, in the Microsoft Authenticator app on my phone, I go to the backup settings and tap on "Details", it shows when the backup was "created" and when it was "last updated". The creation date-time is indeed when I tuned on Cloud-backup - but the "last updated" date-time is only 3 secs later, even though I have since added several 3rd party accounts to the Authenticator.

So what is going on? Is the Cloud-backup not working properly? Is the "last updated" info shown in the app just plain wrong? Or am I missing something? The devil's in the details - and if the details are wrong you can't really rely on the app.