PropertyGrid, how is the behavior different from desiger vs at runtime?

I am having problems with PropertyGrid. Namely:

The behavior is not the same when I use the grid property in visual studio designer as well as at runtime as well as when debugging.

Multiple notes (this is using the form in the designer and editing a custom text box, and nesting a property on a form and attaching it to the same custom text box)

When I have a multiple object selected in the constructor and I set a property (custom type, with a converter), I get a null referenced exception. When I used the SelectedObjects field at runtime, I don't get an exception. If I attach a debugger to the constructor, no exception is thrown and my property setting works correctly.

I have implemented my own expander converter that orders properties. My properties appear in the correct order when I start my application, but they still appear in the default order when using the visual studio designer.

Are there any resources that can help explain why this behavior is happening?

Thank!