If you noticed they behave like this, you could have give them back to the reseller, if it was a reliable one.
And why waiting a year? Doesn't make sense at all.
Devices lost or stolen from companies using Zero-Touch and then found/handed out somewhere and resold will act like that (some kind of theft-protection as not useable in normal behavior).
Don't ask me where i located our stolen devices all over the world already because someone tried to use them again.
