iCloud backup size "0 KB"-- what does this mean?

I should clarify, both devices claim to be backing up, and do list most recent backup times. When I trigger a backup manually, it appears something is being done (it doesn't say the backup failed or anything). But in both cases the final backup size is "0 bytes", "0 KB", or "Zero KB", depending on which menu I'm looking at.

Now, it's entirely possible that these actually are valid backups. But I don't see how anyone could be expected to trust the integrity of a backup that looks like this. I'd check the contents of each of these backups and see specifically what's in them, but of course there's no way to do that. Without being able to do that, no reasonable and attentive person could be expected to believe these backups are good and would be ready to use if needed.

Am I missing something here? Has this been the case for months and I just never noticed until now?

(PS, I'd go make an iTunes backup and rest assured that I had that backup as well. While I do have this on the iPhone, I've never backed up the iPad to iTunes before. In fact, it's the attempt to do a first iTunes backup-- which as I understand it has a low but nonzero chance of wiping the entire iPad in the process of backing it up-- that led me to find this problem. I wanted to make sure the iCloud backup of the iPad is good, so that I could rest assured I had some backup if the iPad was wiped by backing it up to iTunes, I could restore from iCloud, but I don't see that I can count on a "0 KB" backup as a fallback. Things are starting to feel borderline Orwellian.)