Messenger Hyperlinks in Universal GUI

Hi I'm working on adding the hyperlinks for WhatsApp and Viber to an html field in a page in Universal GUI. The links for both messenger apps open installed application in the computer.

but I'm not so successful with Viber. for some reason universal GUI removes the href property of the html <a> element

probably because it doesnt start with https heres a sample. 

WhatsApp (Works)

• Link: <a href="https://api.whatsapp.com/send?phone=0900000000">WhatsApp</a>

Viber (Dont Work)

• Link: <a href="viber://chat?number=0900000000" target="_blank" rel="noopener noreferrer">Viber</a>
• Note1: the viber link works if you search for the link viber://chat?number=0900000000
• Note2: when I inspected the element in developer mode in the browser it seems it is removing the href property of the <a> tag in html of universal page.
• I used an HTML(property) domain to render the html link tag

Is there are rule on how hyperlinks are displayed in Universal? Is there a way to make this work?