Lead Record does not automatically switch to Preferred Custom Entry Form if Lead record's Stage is updated to Prospect

Consider the following Scenario:

Users created the Custom Lead and Custom Prospect forms and mark both as Preferred. However, when a Lead record is converted into a Prospect (manually or by creating Opportunity or Estimate), the form assigned for the Prospect record is still the Lead form.

Steps to repro:
1. Open Lead record in Edit mode.
2. Change Status manually from Lead to Prospect. 
3. Click Save.
4. Click Edit again.

Results:
Lead is converted in Prospect record but Entry Form stays at Custom Lead Form.

Solution: Edit the Custom Lead Form and unmark the option Store Form with Record.