Hi Acme1intl,
Thank you for letting us know.
There can be several reasons for invoices not printing, as a first troubleshooting step, I would recommend trying to print with one of the inbuilt forms rather than the customized form and check if the issue persists as often it has been seen that corrupt logo in the customized forms disrupts the smooth functioning of the printing operation. It would also be worth temporarily disabling antivirus or third-party software to rule out any interference caused due to them.
If the system still does not print, try printing those invoices to PDF instead and if they do print successfully to a PDF printer, the issue would be with printer drivers that would need to be reinstalled. Detailed troubleshooting steps can be found in Printing from AccountRight help article.
Feel free to post again anytime you require further assistance.
Cheers,
Leneth