The .fnt file seems to be the wrong excerpt from the full font, listing a bunch of punctuation characters instead of numbers:
space 18
! 7
" 16
# 17
$ 18
% 17
& 17
' 16
( 17
) 17
* 6
...I made a new .fnt file that works:
tracking=2
0 17
1 7
2 16
3 17
4 18
5 17
6 17
7 16
8 17
9 17
: 3
I'm not sure we meant for the Numerals version of that font to be distributed — apparently we made it for internal performance reasons that don't apply to game development. Does the full version work unmodified? (Roobert-24-Medium.fnt)
Ah, well it was handy -- I wanted a big font for numbers but didn't need any of the other characters, so it seemed like a smaller asset to include in my project. I didn't try the full character set, but I did make my new version of the numerals .fnt file by just clipping the relevant section out of the full .fnt