Per their support, there are known issues which can cause the client and their servers to become "out of sync". If this happens, your backups will stop occurring (even though the app will indicate that the all files are backed up successfully through the current date). The only notice you will receive that this has occurred is after 14 days when they send you an email to warn you that they'll delete your backups if you don't fix it.
They don't seem to recognize why backups silently failing is a very bad thing.
They don't seem to recognize why backups silently failing is a very bad thing.
I stopped using Backblaze after that revelation.