Host Link not working on iPhone

I use a JWT app to crate a host links for my employees to start meetings without being logged into a Zoom account.  The link looks like https://us06web.zoom.us/s/########?zak=eyJ0eXAiO...  This link works consistently on laptops and androids, but recently stopped working on my employee's iPhones.  When the link is clicked (or entered manually in the URL bar) the Zoom app opens but asks the employee to sign in or enter a meeting ID and password, which defeats the reason for the host link.  I have confirmed this issue using both Safari and Chrome - netiher will launch the meeting from the host link. Is there any way to make the host link work on an iPhone?