Good day, @jnamurray.
I'd be glad to provide the help you need. To do so, I need more information regarding the setup and transaction you've made.
Can you clarify if you're using QuickBooks Online to create an invoice? If so, are your QBO and QB Time integrated? How did you add the vendor? Is it on the invoice page? Are you using QuickBooks Workforce, formerly the QuickBooks Time mobile app?
Please know any additional details would help us narrow down the issue. Any screenshots added would be much appreciated. I'll be on the lookout for your response.