[more] works but [!more] doesn't

For some reason suddenly (and I have no idea what I changed.. nothing seems obvious)

<!–more–> has stopped working (loop stops there as it should but shows no formatting such as the [..] Read more I have set up with a filter.

the_content(__('Continue reading →')); // Nothing displayed

add_filter('excerpt_more', 'minimalfolio_auto_excerpt_more'); // Filter to add my special Read more, worked and now doesn't

The filter works with <–more–> but since the WP editor inserts <!–more–> when the more button is clicked this isn’t ideal.

Thanks in advance!

PS. I have already tried deactivating plugins
PS. I have also tested with the default 2010 theme and its still broken – <–more–> works and <!–more–> doesn’t :/