I had this issue last night. Was trying to configure the widgets on the side home screen and next thing I know, a good portion of my folders have disappeared and the apps are now in alphabetical order. It was only some of the folders though. Really annoying since I have pretty much all my apps placed in folders.

Having this problem as well after updating to the public release. Not sure exactly when/how it happened but was playing around with widgets. Next thing I know, at least the apps from the folders on the home screen have been removed from their folders and are in alphabetical order. Had a bunch of folders and don't feel like organizing so just going to restore to backup from pre-update.