AFAIK the answer from Miguel within the link is correct. Maybe your test-server LEF isn't up to date - means the LEF file itself (you may check here: http://lef1.qliktech.com/manuallef/) or the to your account stored data on the Qlik side (you should contact the support).
Yes it's true that QlikView Test Server can fully mirror a Production Server and is best practice to do so. Agree with Marcus in that you should use the Manual LEF Checker URL to determine if the current LEFs of prod and test are identical. If the LEFs don't match up, then reach out to your Qlik account manager for assistance, as Qlik Support cannot assist with modifying licenses.