iOS iCloud Backup and Restore?

Hi,

I am trying to backup my iPad to iCloud to restore it (I know I can also do this via iTunes).

My iPad (latest iOS 12.x) has iAnnotate PDF (for example). When I check in:

General > iPad Storage

it shows 500+MB of documents/data (lots of PDFs).

iAnnotate PDF ... 550+GB (Documents & Data)

I've done an iCloud backup and it has completed successfully.

When I check in Name > iCloud > Manage Storage > Backups I can see the particular backup and it displays as 37.5GB in size.

When I look inside the backup it reports the size as 40.25 GB (bigger for some reason) but the stranger thing is the UI shows: "CHOOSE DATA TO BACKUP" with the different apps, the size of the data, and a slider on-or-off for each application.

Surely that's "choose data to restore"? It's a bit late now to choose what to backup....? Or will that apply to future backups? Strange place to offer this option but perhaps it has to do with it being a long list and saving people jumping back and forward.

Anyway, what is really worrying me is that when I scroll down and find "iAnnotate PDF" (remember it showed as having 500+MB of data in Manage Storage), the entry only has 61KB size. I am worried that it wasn't backed up (and thus I won't be able to restore all the PDFs.

iAnnotate PDF (61KB) Slider = On

Can anyone please explain what is happening?

Thanks,

Ashley.