I've just tried to edit an invoice and a pop up appeared saying "Apply price rules?..." and 2 buttons - neither button does anything and i cant close the pop up

Thank you for bringing this to our attention, @mark-ed-sound. Since you've already tried troubleshooting steps, including using another supported browser, I encourage getting in touch with our Live Support team for immediate action.

Here's how:

1. Log in to QuickBooks Online.
2. Navigate (?) Help on the upper right.
3. Go to Search and then select Contact Us.
4. Enter your concern regarding the pop buttons.
5. Click Continue.
6. Choose either Chat with us or Have us call you.
   
   

Our representatives will review whether this is a technical issue on our end and work to provide a prompt resolution within the product.

You can find our support availability in the Support Hours section of this article: Get Help with Quickbooks products and services.

This article could also serve as a useful reference for personalizing your customer invoices and helping customers better understand the sales form details: Customise invoices, estimates, and sales receipts in QuickBooks.

This will help our support team eradicate the issue immediately and please comment if you have other QuickBooks concerns.

Is this resolved and if so is the solution publicly available?  ( I too have experienced the same.)

I appreciate you informing us that you're also getting the price rule pop-up issue on your invoice entry, jkd1963.
 

To identify the underlying cause of the pop-up problem you encountered, I recommend reaching out to our live support team. They have the tools to review your account securely and ensure this matter gets sorted out effectively.

Refer to these steps to proceed:

1. Log in to your QuickBooks account.
2. Go to the (?) Help icon, then Search tab.
3. Type the "Contact Us" keyword in the designated field. Then, press the Enter button on your keyboard.
4. Click the Contact Us option once it appears on your screen.
5. Choose your preferred method of connecting with our team and follow the on-screen instructions.

Also, please be guided by our team's availability by reviewing the Support Hours section of this link: Get help with QuickBooks products and services.

After finalizing and sending your invoices, you can refer to this article once it's time to record their associated payments: Record invoice payments in QuickBooks.

You can always revisit this thread if you have more questions or concerns.