Problem with String interpolation and space in Label component

[caiqichang]

my code: https://github.com/caiqichang/desktop_pj

i create a winforms project by command dotnet new winforms, and add these code to file Form1.Designer.cs's method InitializeComponent()

var message = new Label() {
    Text = "Nothing",
};

var rock = new Button() {
    Text = "Rock",
    Location = new Point(50, 50),
};
rock.Click += (object sender, EventArgs args) => {
    message.Text = $"Number: {new Random().Next()} ";
};

this.Controls.Add(message);
this.Controls.Add(rock);

Problem:
the random number can not show

if i remove the space after colon

message.Text = $"Number:{new Random().Next()} ";

the random number can show

i have try

Console.WriteLine($"Number: {new Random().Next()} ");

and the whold string ( include random number ) can show in the console.

why ? and how to add space after colon ?