remember after changing the policy a sync has to occur by the mailbox and you have to be using outlook cached mode as opposed to non cached if you havent set that in the policy, once you turn on cache mode you should get prompted
only oter thing i can suggest other than that is scanost.exe as sometimes the hidden message never gets updated in the users OST file so it reads stale configuration settings
https://www.linkedin.com/in/alex-allen-turl-07370146