Folder Tree doesn't remember expanded state of Dropbox for default lister

The Folder Tree remembers the expanded state of all my folders, except Cloud -> Dropbox.

I've noticed that while every other folder is populated instantly, Dropbox takes a few frames to appear after I open a default lister, which I expect is why this happens.
Frame-by-frame of a new lister with "This PC", "Quick access" and "Dropbox" set to expand by default: