I have had an invoice sent to my email from a sub contractor and I can’t view the invoice like I usually do

Hi there, @richbarrdevelopm. It's our priority to ensure invoices can be viewed and sent out properly.

Let's review your Online Delivery preferences from the Accounts and Settings page. Make sure to select the PDF Attached box. We also have the option to include a summary or the full details in the email. 

Here's how:

1. Go to the Gear icon and choose Accounts and settings.
2. Select the Sales tab.
3. In the Online delivery section, select Show short summary in email or Show full details in email.
4. Mark the box for PDF Attached.
5. Click Save and Done.

You can also personalize and add specific info to sales forms. You can also check this guide which provides info on how to print invoices or get a link to share with customers. It also contains links to other processes you can do when using the Invoice feature: Create invoices in QuickBooks Online. 

If you still can't view the invoice, let perform basic troubleshooting. Your browser may have accumulated too much historical data that causes issues like this. Clearing browser caches can resolve it. Let's start by accessing your account through an incognito window to rule out the possibility of a webpage issue. You can refer to these shortcut keys to open an incognito window in all supported browsers:

• Chrome: Ctrl+Shift+N
• Firefox: Ctrl+Shift+P
• Safari: Command+Shift+N

Once signed in, send the invoice again and open it. If you're able to do so, let's clear the browser's cache. By clearing them, you can remove that historical data and access QuickBooks with a clean slate. You can also switch to a different supported browser to see if it has something to do with your browser.

I'll be right here should you need further assistance in managing your invoices. Please don't hesitate to comment down below. Have a good one.