"Send HTML Invoice" Not Sending...
11/18/19 - This issue has been resolved.
11/02/19 - There is a known issue with the HTML Invoice send options, which is currently being worked on by our development team. We do not have a resolution date at this time.
During this period, please feel free to use the "Send an invite to view their invoice" option to email your invoices. This option provides a URL/link to your clients that will allow them to click and view their invoice in HTML format, applying payment as desired or available within your system.
If desired, this email can be edited by clicking Settings/Preferences --> Settings, next to 'Email auto recurring invoices'.