I just had the same problem.
All constants and variables are gone.
Skeletons has remained intact without any connections being deleted, however Conditions blocks have been resized and conditions have changed.
I have tried undoing blocks via the history- nothing has changed. I have tried reloading the project yet it stays the same as mentioned above.
I've tried using a different web browser but still the same outcome.
Please could something be done to restore our projects @fxDreema