DMS | Create Template | Mapping fields gets removed

Environment: PreProd
Steps:
1. Admin login > Create Template
2. Select Source Product > OnBoard [Example]
3. Browse Template
4. Map fields > Address Line 1
5. Change Source Product from OnBoard > SMBHire
6. Map fields get removed from both [Form Field and System Fields]

Expected: MApped fields should be unmapped and should be available in Form Fields

Current: Mapped fields get removed from Form Fields and Mapped field list box.