The only thing I could think of was that maybe you had to have the addon Blizzard_TokenUI active and the currency page open for it to work.
But, looking at
https://github.com/Gethe/wow-ui-sour...okenUI.lua#L66 the 3.4.1 version of the file doesn't seem to have the C_CurrencyInfo. portion of the function.
So, maybe that isn't the problem you are having.