This bug recently started happening to me and restarting Studio doesn’t fix it either.
When you right click and collapse all folds within the script editor, you are unable to open any of the closed folds. You can close folds individually however it’ll only open the top most fold.
Oops! I remember seeing that but I thought it was the bug where close folds but the arrows appear as open. I had that bug a few months ago but the one I just reported started happening a couple days ago, figured it was due to the new update.