Found in betalabs, test2, and production.
- Open a page in VE - click on the sandwich button - Options.
- Go to 'Page settings' or to 'Advanced settings' - modify previously saved settings there: check/uncheck boxes, enter something into available fields etc.
- click 'Cancel' - the Options box will be closed. When you re-open it - the settings that you've just entered and Cancel still are displayed.
The most visible case - click on one of the tabs for 'Show the Table of Contents' - click on 'Cancel', but the action takes place anyway.
"Canceled" settings will be applied upon saving the page.
Note: other Cancel buttons(template, media etc) - they work as expected.