Cannot add nodes

[Marice Sy]

I cannot add child nodes to existing hierarchies. I have had this problem for a few days now.

Repro steps

* Go to your Smart Issue Templates.

* Select an existing hierarchy.

* Click Edit on the upper-left.

* Click Add node at the bottom of the screen.

* Choose a project and issue type from the dropdowns.

* Click the node Summary to open the edit modal.

* Click Add on the bottom-right. Then click Close to return to the Edit hierarchy page.

* Click Update Hierarchy at the bottom of the page.

Expected: I return to the "Manage Hierarchies Page". The hierarchy has been updated.

Actual:  I return to a blank screen with an error notification: "There was an error invoking the function - Data was modified and cannot be read." The hierarchy has not been updated.