If you are creating projects from template and these templates include mandatory fields which are not filled. In the Classic Clarity, users fill them on the creation page and then save. If these mandatory fields are not entered on creation they cannot save the new project and it is not created in Classic Clarity.
In modern UX however, if you are creating a project from template the project is immediately created and you do not get any error message if you navigate out of the project without mandatory fields being filled. The expectation here would be that at least an error message is popping up. Or the project is not even created as it currently working with the creation of projects without a template in the project list of mux. Currently nothing is preventing the user from creating a project without mandatory fields being filled.
New Ux doesn't check for mandatory fields when project is created from template .
Release : 15.X
Component : Clarity Project Management
You can define defaults for those required attributes and then have the user select necessary value.