The Asus Zenfone 4, Zenfone 5 and Zenfone 6 users who were waiting for the Lollipop update will have to wait a little longer. Due to issues with verification, Asus has decided to delay the upgrade schedule.
These Zenfones are using a different chipset (Intel Atom) and there seems to be some limitation of processor issue – New Padfone Infinity (A86), as per the post on Asus forum. For now the Android L upgrade is delayed, however the company will keep pushing security / performance updates for the KitKat OS that is currently running on these handsets.
Asus is working on the related issues and will provide the upgraded soon, it will take some more time, for now they have decided to delay the upgrade to fix issues and provide better user experience.