Prompt for LUKS passphrase during Kickstart on RHEL 7.4

I've read some documentation (from RHEL 6 and 7) that seems to indicate one can omit the

--passphrase

part

part pv.sata --fstype="lvmpv" --size=304220 --ondisk=sda --encrypted

My understanding was this would cause Anaconda to prompt for an encryption passphrase during a Kickstart-automated install, removing the need to include a plaintext passphrase in the Kickstart file.

I've tried omitting

--passphrase