I've encrypted several external USB disks, both Time Machine and regular. On my MacBook running OS X 10.12, I plug it in, a dialog pops in the Finder asking for my password, I type the password, and the disk mounts.
On my desktop running OS X 10.9 this doesn't happen. That is, I plug it in and crickets. I open disk utility and I can see the disk. However when I select it and press the mount button, nothing happens. There are no error messages in the console or any log file I can find.
I can decrypt and mount the disk from the command line using
diskutil coreStorage unlockVolume <UUID>. The question is why it won't ask me for a password in the Finder as expected. Does anyone know a way to fix this?