In my experience, this happens when you try and use some restricted AWD codes. Since your wizard#/Avis1st account is presumably linked to another AWD, the system reverts the reservation to the rate that your profile dictates it should.

It must be programmed that if an AWD is preset from your wizard#, you are not therefore entitled to the restricted AWD, and it removes it.

The only workaround I have found is to get the restricted AWD entered into your Avis profile as your standard AWD, but that is a tricky process and many agents will refuse to do it unless you can prove that you are entitled.