I have backups scheduled for our server (every day at 6PM) to an X: and Y: external usb drive running bitlocker. Sometimes when I plug in either the X: or Y: drive, it doesn't automatically unlock until I manually go in and double click it:
If I forget to check every time, the backup fails that night. Bitlocker is set to automatically unlock both externals so I don't know why this happens. It mounts/unlocks properly %80 of the time.