Hi,
It sounds like a timing issue.
The Save button has been clicked
And then you are testing to verify that the Edit button is displayed
And it is saying that the Edit button is not displayed and yet you can see it is displayed.
After clicking the Save button is there a throbber that you need to wait for?
If there is no throbber then an option would be to add a wait for the Edit button to be clickable.
Something like:
WebDriverWait wait = new WebDriverWait(driver, 15);
wait.until(ExpectedConditions.elementToBeClickable(By.cssSelector("#editButton")));
Cheers,
Adrian.