Hmmm. It's pretty clear that January was killed with the axe, then drained after, of course. The puncture wound is found, and the blood in her body is empty but that spattered about during the fight isn't. So she was drained. But as you note, Gordon says she wasn't backed up. I assumed that meant that whatever reads the memories may not have been "writing to disk" at that time, or perhaps a backup of a dead person can remove the memories from the blood but not store them.

It will be interesting to see whether the backups come up again in a future book, and if so, whether January has a backup (corrupted or otherwise) after all, though.