One thing, that has been a problem for a long time already, has not been fixed in the new UI:
The Start and Stop button in the production (industry) window are in the same place and also look the same. Now it is even worse, than with the old user interface, as the button is not even red any more and looks exactly the same.
It is very easy to hit the stop button and loose all you inputs if you just click two more times on the start button. This can happen easily especially if you start a lot of blueprints of the same type in a row.
It happend to me several times and several other people told me, that it happend to them as well.