There is a capability to create and maintain Financial Plans in the Modern UX. If there are custom attributes in the "Cost Plan" object that have "Value Required" field marked True on them, then an error CMN-0007: Attribute 'attributeid' is required is thrown in the UI. An accompanying screenshot is presented below. Is this expected behavior?
One or more custom attributes in the "Cost Plan" object, whose "Value Required" option is set to True. An error is thrown because, the underlying logic in the application expects all attributes marked with "Value Required" to be filled before a Cost Plan object instance is created. However, there is no capability to configure attributes into the Cost Plan creation page in the Modern UX
Module: Modern UX; Cost Plan; Required Attributes; Studio
To workaround this limitation, all custom fields marked as "Value Required" would need to be changed to set this field to False.
The other option available is to configure a Channel to Cost Plans in the Classic UI.