Cache is the first thing i deactivate while i'm made websites! But i found some other interesting thing!!
You are using this code, for example, in the 'admin/options-page-main.php' file
<?php _e( 'Click to toggle', '__tco__' ); ?>
But in the 'site/content-dock.php' you are using a different text domain!!
<?php _e( 'Do not show again', '__e__' ); ?>
May be that this could be the issue?