Let me help you add time charges to your existing invoices, Ebricks.

First, after ensuring that the Automatically show suggested transactions checkbox is checked, you must click the Suggested transactions and carefully review the active filters. Remove or adjust any filters that may be unnecessarily limiting your results. Here's how:

1. Open the existing invoice.
2. Click Suggested transactions.
   
   
   
   
3. Select Filter and ensure it covers the necessary filters.
   
   
   
   
4. Hit Apply filter.
5. Find the billable time and click Add.
   
   
   

However, if you have already performed all the steps mentioned above, including the basic troubleshooting measures provided by my colleague, JanbonN, but still cannot add the time charges, I recommend contacting our Live Support Team. They have the tools to securely access your account, investigate the problem further, and offer an accurate solution. Here are the steps to contact them:

1. Sign in to your QuickBooks Online(QBO) company.
2. Click Help.
3. Select the Search tab and enter a keyword related to your concern.
4. Hit the Contact Us button.

Moreover, I'll add this resource to guide you in recording customer payments and maintaining the accuracy of your financial data: Record invoice payments in QuickBooks Online.

If you have other questions about managing invoices in QBO, comment below. The Community is always available to respond to your queries.