(in response to eumiramc
)
Hi!
What I just did in my phone to solve it:
1. Activate iCloud.
2. On iCloud settings, activate Backup and create backup from there.
3. On Storage, a backup of 0 KB appeared, I deleted it and then my storage was freed from ghost backup. However, in the iCloud settings, it appeared "3.2 GB available" so...
4. I restarted the iCloud settings and it showed me 5GB again.
From above can comfirm this works. You will have to do it on each device you think may have backup up to the icloud.
Note...Once you re-eanble backup, then on Setting>>Cloud>>Storage>>Manage Storage>> Device Name Backup, wait for this screen to populate with information (i.e the current backup file size in my case ipad 1.4GB & iphone 2GB) then icloud then select delete option below.
Back to Setting>>iCloud and turn off backup again. Bob's your uncle,
Managed to get 3.4GB back myself.