Ok, I just worked it out.
In stardocks efforts to make money they have put in some hooks to make multi monitor support a "feature".
In doing so, if you have more than one monitor attached, even if only one monitor is "switched on", then the extra monitor shows no text.
In my instance, I have a 14" laptop.
Attached is a 24" monitor.
The laptop lid is closed.
Only the attached 24" display is active, and ON. The laptop display is OFF.
Tiles still interprets this as being in "multi monitor mode" and does things that purposely disable the text rendering on the 24" monitor, but renders fine on the 14" monitor.
This is kinda sneaky, and this kind of DRM is a bit over the top.
Definitely not buying this software.
-Ash