This isn’t normal, can you tell me if you were seeing wp-cron.php showing up in your logs on proxycheck.io, or how you concluded that wp-cron is being blocked by the plugin if it isn’t showing up in the logs there?
I will also publish an update that contains some updated code for this wp-cron and a unrelated (but shares the same part of code) fix for people using matomo analytics plugin which may have also been blocked when requests are coming from the servers own IP address. It is possible that this is also your issue and the servers own IP address is being caught up in the check.
May I ask if the original issue is resolved? If I understand your replies, It seems to have been issues with your site/SSL and the plugin is functioning now?