sleep button not working to silence alerts

Recently update ISO for security update. Now sleep/wake button no longer silences text alerts. Even after opening up and reading message alert sound is still going, I have tried searching this problem on the web but no luck. I have read that you can use the volume buttons. Said that doesn't work if your phone is locked thought. Tried restarting several times to see if that would help but it has not.

Anyone else having this issue?