Hello there, Craig_B.
 

I see that experiencing this issue is not ideal. The disappearance of the quantity field is because we have an ongoing investigation about the missing quantity trying to send out their estimates for their customers when they send the estimate. 

While our engineers are looking into this, I recommend contacting our Support Team to add your company details to the list of the affected users. Here's how:

1. In your QBO account, click on the Help icon.
2. Choose Contact us.
3. Provide a brief description of your issue and follow the on-screen instructions.

You can also check these articles to learn more about estimates:

• Create and send estimates in QuickBooks Online
• Convert an estimate into an invoice in QuickBooks Online

Please feel free to reach out to us anytime if you require further assistance with QuickBooks Online. Our goal is to ensure that you always achieve your desired outcomes in your bookkeeping.