Unable to send email

Hello,

I have an issue ‘Unable to send email’ when I click ‘Send reminder email’ in plugin page (WooCommerce->PandingPayments). It may be related with another issue that I see empty columns: Customer and Email in orders table on the plugin page. Customers data (containing email address) is filled up in order.

I have just started using this plugin, so it never works on my site.
I do not see any plugin settings, so I assume that should works by default.

I use 1.0.1 version of plugin, 5.7.1 WooCommerce and 5.8.1 WordPress.