Books on Overdrive vanished after signing in to another account

I have several Overdrive accounts. Actually, I've only been using one account, until a few days ago I tried to switch to another account. Though Kobo stated that the books I borrow from Overdrive will still be there until they expire, all my Overdrive books were recorded as previews and could not be read on the other account. When I switched back to my usual account, the books were back. Would anyone know if I have done something wrong? Thanks!

Apkafe