Hi Mike,
I'm unable to close the discussion/mark as answered as I didn't start it.
The issue I had seemed to be the same as described by Makoto.
To offer a little more detail in my own case. I copied the Fiori MyTimesheet App to a Z-version (extensibility wasn't appropriate) and applied changes to the views/controllers; these changes where not visible at runtime as the original component-preload.js file still contained the original standard code; the changes where visible in debug mode as the component-preload.js file is not loaded in debug mode.
Hope this is helpful for someone else.
Regards, Neil