Hello @Coy Kissee,

I'm sorry you are having trouble meeting your requirements.
What happens is that your code is running before the request to set all Columns state (setColumnState, triggered by the loadConfigs) gets executed.

As a workaround, I would suggest the following:

Add some code to the Javascript of the Web Screen. You can see the sample attached to get better insight.

Note that you will need to override the loadConfigs method in order to trigger a method that will only run after loading the configurations. We are going to call it onAfterLoadConfigs in this example.

Then, you can execute your code, for instance:

GridOS.ExternalAPI.onAfterLoadConfigs = function(gridId){
    var gObj = GridOS.ComponentUtils.getGridObjectById(gridId);
    GridOS.ExternalAPI.extendFilterCombobox(gObj, gridId);
}

GridOS.ExternalAPI.extendFilterCombobox = function(gObj, gridId){
    gObj.filter.getColumnFilter('PO_No').valueFilter.maxValues = 1;
}

Finally, you will end up with something like this:

But please take into consideration that in case of an upgrade of the component you might have to redo the previous steps in order to recreate the workaround.

Hope this sample helps you,

Best Regards,

Tiago Pereira