Audio processing does not happen in audio editor

In the audio editor in Cubase 8.5 pro, when I select a part of a clip and try and apply a process (say normalize or fade in) I get the controls window and can preview the result but when I press ‘process’ nothing happens. Cubase thinks something has happened as the the Undo menu item has the correct process named but the audio file has not changed at all. The only exception is the ‘silence’ process which does work.
I am using build69 (64 bit) on Windows 7.
At the moment Cubase is no use to me and I am going to have to move to another make of DAW if I can’t fix this.

Please help?