Stacked fractions aren't supported by InDesign's fraction making features. To get stacked (or nut) fractions you need a font that has the stacked fractions.
A list of some Google Fonts (all free) that you can use (thanks to @RadLexus):
What you can do is find a similar font and use a GREP style to change the font of the fractions. To create a GREP style to find fractions, you need to set the To Text field appropriately. Since
\d stands for any digit,
\d/\d will make it search for digit/digit.
It's not an ideal solution and it will depend on what actual fractions you need, the font you are using etc. But as far as I'm aware theres no alternative to do this automatically in InDesign.
Or—Make them yourself!
Another option, if your font has a full range of superscript and subscript numerals (or maybe even without, but this would be less ideal, as sup/sub numerals are designed to be shown at smaller sizes) is to use those with a dash (which one I'm not sure, experiment!) to build the fractions yourself. You can set up some GREP styles again to automatically set these to all your fractions.
I won't show you the exact styles because it will vary depending on the font etc, but I just set up some stacked fractions with 3 GREP styles: one for the denominator, one for the bar, and one for the numerator: