Each set of combination codes only works up to the maximum number of sides on that die (except d6), so 6_ON_D4 (like in your screenshot) will display side-by-side instead of overlapping like 1 to 4_ON_D4. However, as long as the numbers are within what you could roll on each die, the kerning should work.
- which version of Dicier are you using (the version number specifically)?
- do the ANY_ON_ wildcard combinations work?
- do the 0_ON_ combinations work?
- which version of Word are you using, on which operating system?
- do you have any other software you could test the codes in? If not, LibreOffice is free and reliable and works more-or-less how Word does, so it could provide a good comparison if there's some quirk in Word preventing certain combinations from working (I no longer have Word, so it's tricky to troubleshoot Dicier in Word myself). You'd also have to install the "otf-LibreOffice" fonts, at least temporarily.