We are currently experiencing an issue in creating new standard sandboxes where users are unable to setup employee reimbursements. We are actively working on resolving this issue as soon as possible. In the meantime, the following is a workaround to configure employee reimbursements:

  1. Go to Admin > Setup > Accounting.
  2. Change Accounting System to QuickBooks (either desktop or online). The Employee Reimbursements tab should now display in the setup wizard.
  3. Go to Employee Reimbursements tab and add employee reimbursements. Now you can add users.
  4. Go back to Accounting and reset the Accounting System to your original value.