We appreciate you getting back into this forum, MonicaG. Let me help route you to the right support available so you can seamlessly send email invoices to your customers.

Since all possible troubleshooting steps were provided and performed in your account, we recommend contacting Microsoft support team to guide you with the following steps to sort out your query. They have necessary tools to further review your file and provide real-time assistance. 

You may also want to visit this article to help fix printing and emailing issues from your company file: Fix PDF and Print problems with QuickBooks Desktop.

Furthermore, I've added this reference to help you track and enter customer paid invoices in your account: Record invoice payment.

You can always get back to us if you require additional assistance managing customer transactions in your file. Feel free to leave them in the comments below, and we'll ensure to provide further help. Keep safe.