After making minor changes, and closing the sketch, it does not ask you to save the sketch and the changes are discarded. I've noticed this with all releases.
Hello @VictorBramhall. I have noticed what I believe is the same problem, and reported it here:
By default, the IDE has the File > Preferences > Auto Save option enabled. So it automatically saves your changes as you're making them. The problem is that with a new sketch or an example, it is saving these changes to the temporary folder.
If you do a File > Save As... to save the sketch to a known location, do you then find that the changes arwe preserved?