Since the value expect the value of "123" instead of 123, we could set the value of the WebInput manually in the button onclick event handler. Here is the snippet:

function WebButton1_onClick() {
    var sVal = "123";
    var input = ISGetObject("WebInput1");
    
    input.SetValueData(sVal);
    input.Value = sVal;
}   

Setting the value manually resolve the issue in my environment.

Hi,

of course you're right, but it's a little bug in SetValueData function.

Regards
Andrzej

Yes it seems this is an issue with the WebInput. A bug report has been submitted, I will inform you if there is any progress or update regarding this issue.

In the mean time, you will need to set the value manually.