Get access to the View row count in the exposed filter block.

I'm not sure if there is a better way to do this, but what ended up working for us was to add a preprocess function to our .theme file like this:

function YOUR_THEME_preprocess_views_exposed_form(&$variables) {
  if(isset($variables['form']['#view']) && $variables['form']['#view']->total_rows) {
    $variables['total_rows'] = $variables['form']['#view']->total_rows;
  }
}

Thanks for reporting, I think your solution should be just fine.

I tried that solution but it did not work for me - and there was no "#view" visible in kint under $vars['form']

Did you remember to replace "YOUR_THEME" with the actual name of your theme in the function declaration?

Yes it is using my theme name, and the function itself is working but no data comes through to "total_rows" - as I say if I add kint to inspect the available variables (into the preprocess function) then I can see $vars['form'] expanded with all the available data - but no sign of "view" or anything remotely similar - only the exposed form data itself..

My form is for a search_api index view - maybe this makes a difference?