First, call your FSA provider customer service to ask why the claim was denied.
You will need to provide the itemized receipt after making a purchase from Hero.
If your claim was denied to due to the confirmation receipt, check to make sure the receipt as everything you need on it: Provider Name, Date of Service, Product Name and Amount
Date of Service has to be a date. If it is a timestamp (i.e Today at 10:27 AM), just wait until it turns into a date. Some email clients use a timestamp for the first 24 hours.