I'm getting the message "Please update the product/service with sales information before marking it as billable.", but I have no idea what it means.

Hello @allanri,

I appreciate you for getting back to us and adding more details about the issue. I can provide some clarification about the message when saving the transaction in QuickBooks.

I've checked the entire thread to know more about the steps you've done on your end. However, I'm unable to view the attachment from your response above.

To ensure you can save the transaction successfully, I recommend reviewing the product or service information. The message usually appears when there's a need for you to review the item details.

Here's how:

1. Click the Gear icon in the upper-right corner, then select Products and Services.
2. Search for the item.
3. Press Edit.
4. Update the information.
5. Hit Save and close.

Also, you should be able to record the expense transaction correctly using the first method. Please try following these steps and check if you still get unusual figures in the invoice:

1. Click the + New option in the upper-left corner and select Expense.
2. Add the vendor under Payee.
3. Enter the expense accounts you want to use for the payment. 
4. Please make sure the expense accounts have income accounts selected for billable expenses (see screenshot below). You can go to the Chart of accounts section to edit the information. 
5. Mark the two companies as billable, then add the amounts and customers.
6. Fill in the necessary information.
7. Hit Save and close.

Once done, you can follow these steps to add the billable expense to an invoice:

1. Click the + New option in the upper-left corner, then select Invoice.
2. Enter the customer name.
3. Add the billable expense. 
4. After clicking Add, you should see the exact billable amount. 
5. Hit Save and close.
6. Repeat steps 1 - 5 for the third company.

For additional reference, I've attached a link you can use about the billable expense feature in QuickBooks: Enter billable expenses.

Please let me know if you need anything else. The Community and I will be here to help you.