Cannot seem to get hook_preprocess_page to work in 8.4.2 Why do I get to the breakpoint in MYMODULE_preprocess_page_title but not in MYMODULE_preprocess_page?

What I am tying to achieve is to update page title both on the top of the page and in the browser title bar/tab name.

The following code only affects the title on the top of the page.

function MYMODULE_preprocess_page_title(&amp;$variables) {
  $variables['title] = 'Something Different!';
}


I've read some people are saying hook hook_preprocess_page instead to update both.

I tried to find what are the available hooks like hook_preprocess_blabla starting here, but couldn't find my way in the documents to the list of available hooks.
both should work on custom MODULE or THEME

function MODULENAME_preprocess_page(&amp;$vars) {
  //do stuff
}

function MODULENAME_preprocess(&amp;$vars, $hook) {
  if($hook == 'page') {
    //do stuff
  }
}


You need to rebuild cache and at least when using netbeans be careful not all lines will trigger the breakpoint ... for example I have noticed that multiline array definitions will not trigger it.  Post your code for more details