I am having trouble adding my accountant. I entered her information, including her email and yet it won't allow me to hit the "Save" button and send an invite.

Try opening your QBO account on any private/incognito browser.

Thank you for bringing this to our attention, @thegrattans. Let’s get your accountant added to manage your company file in QuickBooks Online (QBO).

I have steps that you can take to troubleshoot the issue you’re currently in. Before we start, I’d like to clarify if the buttons to save or send an invite are greyed out. Also, have you encountered specific errors during the process? Additional details are much appreciated.

In the meantime, let’s proceed to logging in to your company file using a private or incognito window the same as what, @4Gal, mentioned. The private window is a helpful tool for troubleshooting browser-related difficulties as it won't preserve any history. The following are the keyboard shortcuts:

• Google Chrome: press Ctrl + Shift + N
• Mozilla Firefox: press Ctrl + Shift + P
• Safari: press Command + Shift + N

Once you have successfully added your accountant, switch back to your default browser and delete its cache. The best way to give your browser a fresh start is to clear the cache or cookies. If not, using one of the supported browsers can also be a smart choice.

Moreover, keep guided in adding or managing users within your company. Adding them will help you with company operations and bookkeeping. 

Let me know about the outcome of the resolution I have added above to ensure that everything works fine. You can add them as a comment by tapping the reply button. I'll be available to assist you with any help you may need.