I'm assuming because I am only using QBO Plus, which does not have job profitability as a feature, that I cannot assign customers to a bill or to bill items.

This is why I was surprised when, if I upload a bill / receipt, I do have the option to assign a customer to a bill or bill items (although I get an error if I try to mark it as a billable expense - the error says my plan does not support billable expenses). But if I keep the box unchecked for making it a billable expense, I am able to save the bill with the customer name assigned.

However, once the bill is created, there is no customer field on the bill (meaning I cannot edit the customer after I complete the bill upload process).

I am sharing screenshots to show the bill creation (assigning a customer), the bill edit screen (showing no customer assigned), and the Profit and Loss by Customer (showing the bill is assigned to Sample Customer).

I do not really expect this to be resolved, I simply wanted to offer it to the community as an FYI.