What you describe is correct as far as you went. First, make sure you have read this Guide:
https://forum.manager.io/t/how-to-use-expense-claims/6898
Perhaps when you Spend money to pay the claim, you are allocating that transaction a second time to the expense account involved? The correct allocation is Expense claims => Payer. Of course, the person being reimbursed (who is the Payer) must have been created as an expense claim payer before entering the original expense claim. Otherwise, no liability to pay that person will exist in the database.