I get the same behaviour, but I always assumed this was by design. Taking a simple example, I have the C# snippet
if ($end$)
{
$selected$
}
which also has the shortcut "if" assigned to it. Obviously there is nothing to insert in the place of $selected$ when this is triggered with the shortcut, so the insert menu is just doing the same as typing the shortcut.
Some of the snippets don't have shortcuts, so they aren't listed on the right hand side of the menu, but you can still insert them with nothing selected, even though this may well be less useful.
