Quick launch four levels

Hello experts!

I have some issues/questions regarding the modern page (SPO) Quick Launch menu. I will cover each question in separate posts. Here is the first one.

It is possible to have four levels of navigation in the Quick Launch menu. However, it only works one time. Is there any way to fix this?

To recreate the issue i edit the node "Bok0-0F".

After saving, the fourth level is visible.

But after clicking it disappear again.

As you can se below the menu items are there.