Hi Nascarfan, what exactly do you mean with a kepub being "locked"? Does it not sync to the right bookmark? Perhaps it has something to do with the order in which you sync you devices. If the most recent bookmark is on the Glo and you sync the Kobo Wifies just before you sync the Glo, the Wifies won't get the most recent bookmark...
If that' not the problem, please explain what you mean by "locking."