Welcome back, @TerriSR.

Allow me to provide information on how billable expenses work when converting them to an invoice.

The expense category selected in a billable expenses transaction won't show on the invoice upon converting it. Please know that the invoice is a sales transaction, and there isn't a way to choose or associate an expense category with it. 

If you want to show the expense category as your sales transaction, you can create a journal entry. However, I recommend seeking help from your accountant to guide you on which appropriate category or account to select. If you don't have an accountant, you can find one through this link.

You might want to review all your sales transactions made in QuickBooks Online. You can go to the Sales menu and select All Sales.

Please let me know if you need clarification about converting billable expenses to an invoice. I'll be standing by for your response, @TerriSR.