Refer to the code in https://github.com/jleyva/moodle-block_configurablereports/blob/f63cf94c9f14d5ce36d872c2cd67179a571db530/block_configurable_reports.php#L183:

$lastcron = $DB->get_field('block', 'lastcron', array('name' => 'configurable_reports'));
*if (!$lastcron and ($lastcron + $this->cron < time()) )*

Should that if() statement use *!$lastcron* or *$lastcron*?

See the comments in https://moodle.org/mod/forum/discuss.php?d=429769 and https://moodle.org/mod/forum/discuss.php?d=409387

Issue discovered on:
$plugin->version = 2020110300;
$plugin->release = '3.9.0';