The problem is solved. A simple example was built using FXML and combining the GUI from the failing FXML program with code from the working non-FXML example and the failing FXML based program. The result works correctly for zooming with both slider and the scroll wheel, and panning to the edges of the image with zoom factors from 0.2 > 5.0, which is the eventual desired range. A test image is provided.

The only problem remaining is that when the image is zoomed smaller than the scroll pane, the image is not centered. Work continues.

The reason for the failure of the initial attempt or the first simplified program is not known.

Code for the working FXML based example is at:

https://github.com/windyweather/PanImageTwo

Thanks for your help.