It's on a custom page that we created. Here "Default value" script:

I need return value in here and I don't know what the format should be? Is format of the data returned in script depends on where filter is being placed?

We opened a hi ticket on this. they provided this format and it works

1. Using static default value:

return [{
available : true,
id : "dfsdf7sd6f7sdf6dsf",
label : "Option 1"
},
{
available : true,
id : "7657765fsdfsdfsdf567",
label : "Option 2"
}];

Did you find the solution for this? I have a similar requirement

You can use the format below to set up the Default value. Below is an example of a Default value with a data source as the User table: