Check visibility on required custom fields

app/models/projects/custom_fields.rb

@@ -42,7 +42,7 @@ def available_custom_fields
       return all_visible_custom_fields if new_record?
 
       all_visible_custom_fields.where(id: project_custom_field_project_mappings.select(:custom_field_id))
-                               .or(ProjectCustomField.required)
+                               .or(required_visible_custom_fields)
     end
 
     # Note:
@@ -64,6 +64,10 @@ def all_visible_custom_fields
       all_available_custom_fields.visible(project: self)
     end
 
+    def required_visible_custom_fields
+      ProjectCustomField.required.visible(project: self)
+    end
+
     def custom_field_values_to_validate
       # Limit the set of available custom fields when the validation is limited to a section
       if _limit_custom_fields_validation_to_section_id