Garbled text fixed by refresh

The main navigation:

<?php wp_nav_menu( array( 'menu' => 'main', 'container' => false, 'items_wrap' => '%3$s' ) ); ?>

and section labels, eg:

<h3><a href="<?php echo get_post_type_archive_link('project'); ?>">PROJECTS</a></h3>

render text incorrectly –?alphabetically one letter earlier than intended. For example, ‘Home’ renders ‘Gnld’. This fixes itself with a refresh. I’ve looked at character encoding, font loading but to no avail –?any help/suggestions/guidance very welcome!