All I know is that I have two guildies who are stuck with NO specialization because they did one, crafted all the trinkets and then abandoned to relevel only to find they cannot get the opposite spec.
I’m gonna check the bug report forums to see if there has been any traction on a fix yet one min.
EDIT : Here is the most recent post on the subject as far as I’ve been able to find. It’s still not working for most people so I advise choosing carefully and sticking with your choice for now.