I checked and the clientIDMode is set to AutoID. I made a new master page and test page and I'm not sure what I'm missing to refresh the label on the client side. Below is the simple example that I created :
Master Page .ASPX
Master Page Code Behind:
public void Press()
Sample Page .ASPX:
Sample Page Code Behind:
public void Press() gets called from the button press but the label "lblUpdate" does not get refreshed on the
client side.