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