My customers cannot view the invoices I send on my last few, the view invoice button opens nothing....any ideas?

Let me share this workaround I have, @david218.

In the meantime, you can resend back the invoice that has the issue. By doing so, the customer able to see the invoice PDF now. Let me guide you on how.

1. Go to the Invoices tab and select Create invoice.
2. Select the Invoices section. 
3. Scroll down and locate the invoice and click on it to open the invoice. 
4. Click Send invoice.

I've also added an article about "what's new with QuickBooks Self-Employed Invoicing?" This will provide you the details about the recent update that we released to enhance customer's experience when creating an invoice.

Here's an article you can read on for more details: Create an invoice in QuickBooks Self-Employed (QBSE).

Please keep on posting if you need more clarification. Take care.