Problems with Encrypted CI Session

[eluser]CodeIgniterNewbie[/eluser]
I set the following flashdata:

Code:

$this->session->set_flashdata('my_data', $my_data);

Then, on the next page, I am able to access it via:

Code:

var_dump ($this->session->flashdata('my_data'));

However, when I enable encryption, all I get from the var_dump is a false. This makes the session data useless, of course. What is going on? How am I supposed to access encrypted session data?