Just to add that even though my ACF block was registered with underscores in the name, these had to be replaced with hyphens in the allowed_block_types() function for it to work!
add_filter( 'allowed_block_types', 'custom_allowed_block_types' );
function custom_allowed_block_types( $allowed_blocks ) {
return array(
'acf/single-text-column',
'acf/text-image-block'
);
}
Hope this helps someone 🙂
