Lead Conversion Does Update To The Prospect Form

We have created custom Lead and Prospect forms for our sales team. Very recently during some training I found that when using the convert button, and completing the steps for conversion, the resulting record does not save into the preferred Prospect Form. The conversion process is successful in making the lead into a prospect and creating a contact, opportunity, and task. However, the original lead form for stays loaded with the customer record, instead of the prospect form. We can of course just manually change the form view to our prospect form. But originally this process was working correctly so