According to Christoph Knittel on the TKL forums the OpenLDAP database is not being backed up, nor can it be without stopping the service. Christoph has provided a tklbam-hook in this post
Howard Chu provided some additional info in regards to other options (to allow backup of live/running system.
Eric has provided hook and restore scripts for inclusion into TKLBAM.
Eric's work was tweaked by Christoph and eventually added to TKLBAM profiles by @lirazsiri via turnkeylinux/tklbam-profiles@d12462f
See Liraz's comment and details in this forum post
As per my comment in the forum, this issue has been fixed. Great job everyone.
PS: I could have sworn I closed this yesterday but I don't even see my comment, so I must have not clicked the 'close and comment' button.