What the drush cr would do that the flush all caches would not? Particularely regarding block caching?
I got mad trying to set a custom block twig template for eventually figuring out that nothing was wrong with my code but flush all caches was not enough and drush cr would do the job.
EDIT: could there be a bias of my local dev settings ?
$settings['cache']['bins']['render'] = 'cache.backend.null'; $settings['cache']['bins']['dynamic_page_cache'] = 'cache.backend.null';