Invoices wont Email

Hello, I have an updated version of Wp-Invoice running, but our invoices recently stopped emailing. The plugin states that they were sent successfully and records them as sent, but the emails never go out.

They sent successfully for a long time and have just recently stopped emailing properly (I cannot say for sure if it is related to the last plugin update or not).

Here is a screenshot: https://awesomescreenshot.com/0845fezkbe

Any help is greatly appreciated!

https://www.ads-software.com/plugins/wp-invoice/