Has anyone gotten the error “this customer or lead does not belong to your group” when trying to open a customer record as the sales representative role?

I forget where it is, but there's some functionality to prevent reps from seeing leads/prospects/customers outside of their own or their own team. Sounds like you have that turned on. My first guess would be the employee record, but some searching of SuiteAnswers should turn it up if no one else posts a better answer here.