I would suggest disabling the library and drives in BE (right click and un-check the enable line), then delete the drives and library from BE, then stop BE services, then restart BE services and let it re-discover your library and drives.
If that doesn't fix it, please check the adamm.log (or post a copy here) for any weirdness or error messages.
Was anything else changed besides the library firmware? What was the old firmware version?