Hello, I wanted to test the hierarchy feature in model driven app, so I followed this tutorial, but I got an error, this is my step:
First, i created an entity, in this entity, I created a lookup field that lookup to itself:

Next I go to the classic view of my solution, and update the 1:N relationship to hierarchy:

Next I created a new form, I named it HierarchyForm:

Then I went to the entity Hierarchy setting, and created a new Hierarchy, I used the form that I just created, and select the relationship that I updated above:

I published my customization and opened my Model Driven App, I was able to see the hierarchy icon next to the items:

But when I clicked the hierarchy icon, I got this error:

I tried to change and update the form but it still the same. Can somebody help me with this ? Thank you for reading.
Best Regards,
Minh Pham