"Class" is mandatory field but when I select Class from receipts and try to create expense, I get error message "Missing Class" "Are you sure..Y/N ?

Thanks for posting here in the QuickBooks Community, @aniz-premiuminno.

I'm here to share some insights on how to rule out this problem. Have you tried opening the invoice in a private window?

Unexpected issues in QuickBooks are sometimes affected by the amount of data stored in the cache. This is because a regular browser will constantly overwrite itself and will not remove history unless done manually.

Private browsing will not save any history, so it's a great place to identify issues in the browser. Use these keyboard shortcuts to launch a new private window:

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

Do the match ans see if the error comes up again. If it works, clear the cache to resolve browser issues in QBO. You can also use a different browser and see if the issue persists there.

If none of it works, I do recommend contacting our Support Team this time to get the issue reported to our engineers. You can request a representative to create a case ID for you and have them escalate this problem to our Technical Team.

To get a hold of a representative to check your account, follow these steps:

1. Go to the Help menu then choose the Search tab.
2. At the bottom click on Contact us.
3. Enter the keyword Account Management and Billing in the What can we help you with? box.
4. On the next screen, scroll down to How would you like to connect with us section.
5. Choose your contact option to connect with a live agent.

For your reference with matching transactions and reconciliation workflow, see the following links:

• Categorize and match online bank transactions in QuickBooks Online
• Learn the reconcile workflow in QuickBooks

Post here again if you need further assistance with this invoice processing concern. I'll be right here to help you anytime. Have a great day!