SU - Save Current Window Size Not Working

This may be a Mac only problem, but …

The file keeps reverting to a smaller window size compared to my display size. I can resize the workspace window by dragging the handles to full screen, then use SU>Preferences>Workspace>Save Current Window Size, followed by a file save. On reopening, the workspace does not fill the display as set previously.

I also tried, model info>purge>fix. Also tried workspace>reset.

I found a reference to a similar issue, but uses the same approach I have tried.

The image shows the left hand side, but there is a larger gap on the right side.

Any help, much appreciated.