I have created a multibranch pipeline job and configured global HipChat notification settings to send a message on build failure. No messages are being sent when these jobs fail.

I also tried to set the hipchat notification in the Jenkinsfile using HipChatJobProperty, which failed to work as well.

properties([[
        $class: 'HipChatJobProperty',
        notifyFailure: true,
        notifyBackToNormal: true,
    ]])

Using hipchatSend() does work, and appears to use the globally configured credentials and room values.