systemd: truecrypt fails to mount with "Failed to set up a loop device: /my-data-file.tc"

[Zenaan Harkness <zen@freedbms.net>]

When booting with systemd, I can no longer mount truecrypt volumes,
with a pop-up error window displaying this message:

Failed to set up a loop device: /my-data-file.tc

Any ideas?

This has not happened normally - I use truecrypt every day just about.

TIA
Zenaan