Hello Martin,
I’m having the same issue on 8.6.013. Did you ever find a solution to your problem?
We downgraded all our thin clients to 8.6.013 recently, because some of our thin clients get stuck in a reboot loop since we started using wyse management suite. Ever since the downgrade we have had users lock them selves out of AD after one bad password. I guess upgrading to a newer firmware would resolve this issue. But for us this brings other more detrimental issues.
Kind regards.