Mounting Airport Connected HD fails in 10.8
I have a 1TB USB drive attached to my Airport Extreme. The volume is selected as a login item under my account in system preferences, and sharing is turned on in the Airport Utility. The attached drive has been verified and permissions are OK.
I use this disk for occasional 'on-the'fly' backups and also, using Backup 3.2, I have a daily schedule that automatically backs up essential files, much like I used to use for 'personal data and settings' in the days of iDisk.
This all worked reliably with Lion 10.7.4
Now, with M. Lion, the USB disk no longer mounts automatically, and my Backup script hangs saying 'waiting for volume xxxx'. If I click on Airport Extreme and 'Connect' and choose the attached disk, all work as expected, and backup kicks in and runs successfully.
Is this a change in M.Lion behavior which I don't know about, or a new Finder bug?
TIA
iMac, OS X Mountain Lion, 16 GB RAM