Latest version on Win10.
A test project has enough Chapters to require scrolling the Document Tree.
When I click the triangle to collapse folders, the last few won’t collapse unless I scroll up and down a little, just once for each folder I’m trying to collapse. This may be related to making the tree scroll down as the overall depth is reduced by each collapse.
Opening a closed node also frees up the Tree for one more collapse action, but then it won’t allow any more nodes to be closed.
I made a Tree Scroll Bug video which makes it a lot easier to understand what’s happening.