Tested with 3 fonts: Lucida Sans, Lucida Grande and Lucida Sans Unicode.
Lucida Sans: No problems with ¼½¾.
Lucida Grande: No problems with ¼½¾.
Lucida Sans Unicode: Problems with ¼½¾, contours should be overlapped into "Corrupted Fractions".
Look at the image to see corruptions with ¼½¾.
MS DOS Latin 1 has this ¾ fraction.