It is allowing to hide the mandatory fields

Steps to reproduce

• login
• navigate to the contact custom field
• navigate to the first name field
• click on edit -ref
• now enable mandatory field-ref
• now disable the show field -ref
• click on save
• now first name is hidden although it is mandatory
• now re-activate the first name field
• try to hide it again by keeping it as mandatory
• it is not possible -ref