Created Unassigned: Raised event of InteractionRequest becomes null [10735]

Hello,

We have a view that opens a UserControl (UC1) as a popup using InteractionRequest<INotification>.
UC1ViewRequest.Raise(new UC1ViewModel
{
Title = "User Control 1"

});
UC1 has a button that opens another UserControl (UC2) as a popup using InteractionRequest<INotification>.
UC2ViewRequest.Raise(new UC2ViewModel
{
Title = "User Control 2"

});
Opening UC2 again and again from UC1 works fine as long as UC1 is not closed.

But after closing UC1, UC2 cannot be shown/opened from UC1 but UC1 can be opened again from the main view.

The Raised event on the UC2ViewRequest is null.

Please advise. Attached is the sample to reproduce.