I might not be explaining this well due to a different issue, but…
When a book has multiple hierarchical levels in the leftmost notebook pane, if you switch to a target book via Detail and then move back up one level, clicking or selecting a book does not respond.
It looks like remnants of multiple layers remain.
For example, in some cases, a div tag exists in the book’s position, seemingly obstructing interactions.
I’ll observe the behavior a bit more, but that’s it for now.