ThemeMagic is not loading global variables declared in a separate variables.less file in the local folder

I have created a separate styles.less and variable.less files in the templates local directory to isolate my template changes.

I am able to create a new THEME and add these variables and save the theme.

However, when I then go back to the theme and try to make further changes I cannot because I am getting several error messages like 'NameError: variable @what-ever is undefined'

The front end works fine in development mode, I can also compile the theme LESS to CSS without any errors.

Is this a known issue?

How do I work around this?

Do I also need to create another variable.less file for local/themes/theme-name?