Command Input Syntax Colouring

Code:
c:\users\jlc\utils>ver

TCC  23.00.30 x64   Windows 7 [Version 6.1.7601]

I have command input Syntax Colouring enabled;
1539689180098.png


This seems to be working okay...
1539689222496.png


...but if I use environment variables that start with an underscore...
1539689278475.png


...there is no syntax colouring.

Is this WAD?

Joe