Why is the font on my x axis unable to be set above some maximum font size?

Probably the best way to explain this is to link to the stackoverflow question I posted but got no answers from.

The essence of the problem is that no matter what I set Layout.xaxis.tickfont.size to, the end result is always capped at 12px. And here is where this is very odd: it is computer-specific. Thus, on my colleagues computer if he sets tickfont.size equal to 24, it renders tic labels in 24 point font. However, on my computer it does not. Even more odd, it works on all browsers for him, but fails on all browsers for me even though our (git) code is synchronized.

Here is the posting: