We are experiencing issue with creating and saving an invoice

Hello, kireeshan. 

Let's work together to find a solution to the issue you're experiencing. Have you tried opening your account using an incognito/private browser? It's possible that you are experiencing a browser problem. Sometimes temporary internet files like cache and cookies can help speed up your browser's performance, but having too many of them can negatively impact your experience on QBO.

To start the troubleshooting, you'll want to access your company in an incognito or private browser. You can use these shortcut keys:

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

Once it works properly, I recommend clearing your browser's cache before returning to your regular browsing activities. If you are experiencing difficulty with private browsing, it may be helpful to use different browsers. This will ensure you have the most secure and optimal experience when using QuickBooks. For additional information on system requirements for QuickBooks, please refer to the following article: System Requirements For QuickBooks.   

If the issue persists, I recommend contacting our customer support team. This way, one of our agents can check your account and investigate this further.  

Here's how to reach them:

1. Sign in to your QuickBooks Online company.
2. Select the Help (?) menu.
3. Choose the Assistant tab.
4. Click the Talk to a human option.
5. Press Get help from a human.
6. Tap either the Chat with us or Have us call you button. 

In case you want to modify your sales form for future use, I've also included this resource: Customise invoices, estimates, and sales receipts in QuickBooks Online. 

Don't hesitate to post again if you need anything else in QuickBooks. We're happy to help.