Can't get a Redirect Hook to Fire
Good afternoon.

1) install the devel module.

2) Install the modules, devel, kint.

3) change your code for the following:

function my_module_redirect_alter($redirect) {
   dpm($message = "redirect_alter worked!");
   kint($redirect);
}


4)  try to perform a process such as updating a node and when redirecting, you must show the messages.

Note: dpm() and kint() are functions of the devel module to inspect a variable