Custom blocks are looked up by delta, not bid as the description states

The code of the function block_block_view($delta = '') is:

function block_block_view($delta = '') {
  $block = db_query('SELECT body, format FROM {block_custom} WHERE bid = :bid', array(':bid' => $delta))->fetchObject();
  $data['subject'] = NULL;
  $data['content'] = check_markup($block->body, $block->format, '', TRUE);
  return $data;
}

This looks like it will lookup by the bid. It will however look up by the (numeric) delta of the block.

The description of the schema states that wrong, as well:

$schema['block_custom'] = array(
  'description' => 'Stores contents of custom-made blocks.',
  'fields' => array(
  'bid' => array(
    'type' => 'serial',
    'unsigned' => TRUE,
    'not null' => TRUE,
    'description' => "The block's {block}.bid.",
  ),
  // [...]
);

Relying on the wrong docs here leads (of course) to:

Notice: Trying to get property of non-object in block_block_view() (line 246 of /var/www/consolero/modules/block/block.module).

And of course you can't join {block} and {block_custom} by bid, as you would expect. You must join by the deltas and the condition module='block'.

I think this should be changed to delta in all cases.

-- Kind regards, Niklas