I can confirm this bug on my system as well. I have the whole disk encrypted instead of a partition (say /dev/sdb instead of /dev/sdb1) and although the password box shows up, nothing happens when I enter it. If I attempt accessing the disk again, I'm once again asked for the password. The only way around this problem is to manually cryptsetup and mount the disk.
I can confirm this bug on my system as well. I have the whole disk encrypted instead of a partition (say /dev/sdb instead of /dev/sdb1) and although the password box shows up, nothing happens when I enter it. If I attempt accessing the disk again, I'm once again asked for the password. The only way around this problem is to manually cryptsetup and mount the disk.