This is a random bug, it happened 2 times with different scenarios.
The Save button and the Discard changes one just disappear as well as the statusBar they are in, making impossible to save without opening other feature and make the popup to save changes appear.
resizing the window does not change anything, only refreshing the page
Create a new schema
Add more than 6 fields in it, the studio screen will scroll down automatically.
=> The bar disappears.
The bug is still there even if you turn off your adblock.
Resize the window using the restore / maximize button and the bar appears again.