ImGui package not working

[MechSlayer]

Hi, I tried to use the ImGui package following the Lab/ImGui example, but for some reason is not showing anything.
I tried using OpenGL 4.6 Core with a GLFW window.

Here is an example

//ctor
// window.View is a IWindow, and window.Input is a IInputContext
GuiController = new ImGuiController(glContext, window.View, window.Input);

//OnRender
GuiController.Update((float) deltaTime);
GlContext.Clear((uint) GLEnum.ColorBufferBit);
ImGui.ShowDemoWindow();
GuiController.Render();
Window.SwapBuffers();