It looks like Outlook made another update on January 13, 2017 --> https://play.google.com/store/apps/details?id=com.microsoft.office.outlook&hl=en
Email code that worked perfectly before is now showing hidden preheader line when viwed in Outlook mobile app.

Here is what I am currently using to hide preheader:


div.preheader { 
    display:none !important; 
}

<div class="preheader" style="font-size: 1px; display: none !important;">My preheader here</div>

Any suggestions on how to fix preheader in Outlook Mobile app are much welcome.

Thank you,
Elina