I just wanted to add my 2 cents, that the ctrl_shift is not working for my broken folders. My folders did seem to break after I moved some parts around in the arranger.
You can see in this image, it did un-collapse my drum folder, however all my other folders show as if the are un-collapsed, but they are not!
'
edit: of course the next thread I opened had solved this issue. I just had my tracks hidden somehow (new to me!) and pressed "h" to bring up the hiding manager. My tracks are back now, yay!
