Active directory integration - users disappearing

[Russell Jones]

I'm trying to set up AD integration on my trial server. I've filled in all the settings and run the tests, and they report that 34 users are imported. So I kicked off a Sync and went to the Users screen, which showed me that there were 4 pages of users. I moved to the final page, but when the screen refreshed it showed me that there was now only a single page, and nearly all the users had disappeared from the list - only two remained. What's going on - why does Jira import 34 users and almost immediately delete 32 of them?