When ASUS started updating a few of its phones to Android Pie, it ran into issues for some models, including the Zenphone Max Pro M1 (ZB601KL) and Max M2 (ZB632KL). Their upgrade was supposed to roll out in March, but the company had to apologize and delay the release to mid-April. True to its word, ASUS is now pushing the new software to the first devices in a staged distribution, starting in India.

To check your phone for the update, head to "System updates" in Settings -> System. As it is customary for Android (except for Pixel phones), you may need to wait a couple of days or weeks until your device is blessed with the new software.

Back in March, ASUS also promised to put Android Pie on the Max Pro M2, so it's fair to assume that it will soon receive its share of the cake, as well.

Source: ASUS Zentalk Forum (Max Pro M1), (Max M2), (Max Pro M2)