MAX98357A I2S Amplifier and Raspberry Pi 4 - Volume Control from IPhone not working

I have an Adafruit Max98357a i2s amplifier connected to my raspberry pi 4.
Installed volumio onto micro sd via raspberry pi imager.
Volume is working fine however I am not able to control the volume from my iPhone
using the volume controls on the side of the iPhone.
Can anyone help to advise please.