If the last text you edited was a in a label, and then you open up a signal producer which has a shape with empty layers in it to edit it, the pre-filled text for what was inside that signal producer will be flattened. You can exit out of the signal producer without saving and reopen it, and the pre-filled text will be exactly what it should be instead.
Sorry the screencap doesn't show the mouse, if it is hard to follow it's:
- showing what's in the signal producer
- opening the label
- opening the signal producer to show off the flattened shape, closing out of it without saving
- reopening the signal producer to show that everything is normal if the label wasn't the last thing opened
- reopening the label
- and reopening the signal producer, but this time closing out of it by clicking save, thus saving the flattened shape and screwing stuff up