Currently, the Wizard displays any server-side errors that are added to the ModelState in the respective form fields within the Wizard steps (which is great).
The problem is that those errors are not "cleared" when the field is edited/changed. This prevent the form from being posted or the user to move to the next step if the form validation is enabled within the Wizard.
The only way to work with server-side error in the wizard form at the moment is to either disable form validation altogether or to attach an "onchange" event to each of the fields and clear any server-side errors manually once the field is changed.
Both solutions are far from ideal. It would be great if this was part of the default behaviour of the wizard form (like it already is for client-side errors).